JP2021196553A - Image output device - Google Patents

Abstract

To provide an image output device easy to enlarge a stereoscopic image.SOLUTION: An image output device 1A includes a high-speed projector 2A, a spatial light modulator 3, and an address light irradiation section 4A. The high-speed projector 2A has a principal surface 3a and a rear surface 3b, reflects light E1 emitted to the principal surface 3a, and modulates a phase of the light E1 for each of a plurality of pixels arranged two-dimensionally. The high-speed projector 2A irradiates the principal surface 3a with the light E1 including a two-dimensional optical image. The address light irradiation section 4A irradiates the rear surface 3b with address light E2 including a diffraction grating pattern. Each pixel of the spatial light modulator 3 changes a phase modulation amount according to the intensity of the address light E2 emitted from a side of the rear surface 3b of each pixel. The address light irradiation section 4A dynamically changes the orientation of the diffraction grating pattern on the rear surface 3b. The high-speed projector 2A irradiates the principal surface 3a with the two-dimensional optical image corresponding to the orientation of the diffraction grating pattern.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an image output device.

Non-Patent Document 1 discloses a device that outputs an image in three dimensions. The device comprises a holographic screen that rotates at high speed (3600 rpm) and a high speed projector. The high-speed projector is a DLP (Digital Light Processing) projector using a DMD (Digital Micromirror Device). A high-speed projector irradiates the holographic screen with a two-dimensional light image, and the holographic screen rotates at high speed to deflect the two-dimensional light image in the entire circumferential direction of 360 °. The high-speed projector changes the two-dimensional light image corresponding to the deflection direction of the holographic screen. This makes it possible to make the image appear three-dimensional to the observer.

Non-Patent Document 2 discloses a technique relating to an optical address type liquid crystal spatial light modulator (PAL-SLM). This spatial light modulator includes an address layer and a liquid crystal layer. The address layer contains hydrogenated amorphous silicon which is a photoconductor. The liquid crystal layer contains a nematic liquid crystal. The write side and the read side are optically separated by a dielectric mirror made of a multilayer film of _{SiO 2} and TiO _2. An AC voltage of several volts is applied between a pair of transparent electrodes (ITOs) sandwiching the address layer to write an image (two-dimensional information) on the address layer. In the region not exposed to the write light, the impedance of the hydrogenated amorphous silicon is larger than the impedance of the liquid crystal layer, so that almost no voltage is applied to the liquid crystal layer. On the other hand, in the portion irradiated with the write light, the impedance of the hydrogenated amorphous silicon decreases and the voltage applied to the liquid crystal layer increases, so that the phase of the read light in the liquid crystal changes. In this way, the phase of the read light can be two-dimensionally modulated according to the write light information.

HideyoshiHorimai et al., “Full-Color 3D Display System with 360 Degree HorizontalViewing Angle”, The International Symposium of 3D and Contents 2010, pp. 7-10 (2010) Tsutomu Hara, "Recent Developments of Liquid Crystal Spatial Light Modulation Elements", Optics, Vol. 36, No. 3, pp. 122-128, 2007 Yoshitomo Isomae et al., “Alignment control of liquid crystals in a1.0-mm-pitch spatial light modulator by lattice-shaped dielectric wallstructure”, J. Soc. Inf. Display 27, pp. 251-258 (2019)

Non-Patent Document 1 discloses a device that makes an image appear three-dimensional by outputting a two-dimensional optical image corresponding to each direction in the entire circumferential direction of 360 °. However, in the device disclosed in Non-Patent Document 1, it is difficult to increase the size of the holographic screen because it is necessary to mechanically rotate the holographic screen at high speed. Therefore, there is a problem that it is difficult to enlarge the stereoscopic image. Therefore, it is an object of the present disclosure to provide an image output device that makes it easy to enlarge a stereoscopic image.

The image output device according to one embodiment has a main surface and a back surface, reflects light radiated to the main surface, and spatial light that modulates the phase of light for each of a plurality of pixels arranged in a two-dimensional manner. It includes a modulator, an image irradiation unit that irradiates a two-dimensional light image on the main surface, and an address light irradiation unit that irradiates an address light including a diffraction grating pattern on the back surface. Each pixel of the spatial light modulator has a configuration in which the phase modulation amount is changed according to the intensity of the address light emitted from the back surface side of each pixel. The address light irradiation unit dynamically changes the direction of the diffraction grating pattern on the back surface. The image irradiation unit irradiates the main surface with a two-dimensional light image corresponding to the direction of the diffraction grating pattern.

According to the present disclosure, it is possible to provide an image output device that makes it easy to enlarge a stereoscopic image.

It is a perspective view schematically showing the whole structure of the image output device 1A which concerns on 1st Embodiment. It is sectional drawing of image output apparatus 1A. It is sectional drawing of the spatial light modulator 3, and shows the cross section which intersects with the main surface 3a and the back surface 3b. Part (a) is a partially enlarged plan view of the partition wall 39a. Part (b) is a partially enlarged perspective view of the partition wall 39a, and shows the structure in the vicinity of the partition wall 39a upside down. Parts (a) to (d) are cross-sectional views showing each step in the method of manufacturing the spatial light modulator 3. Parts (a) to (d) are cross-sectional views showing each step in the method of manufacturing the spatial light modulator 3. FIG. 3 is a plan view of the light emitting device 41 as viewed from the axial direction of the annulus. It is a front view which shows the light emitting surface 42a of one light emitting part 42. It is a figure which conceptually shows the state of irradiating the address light E2 on the back surface 3b of the spatial light modulator 3. It is a figure which conceptually shows the state of irradiating the address light E2 on the back surface 3b of the spatial light modulator 3. It is a figure which conceptually shows the state of irradiating the address light E2 on the back surface 3b of the spatial light modulator 3. It is a figure which conceptually shows the state of irradiating the address light E2 on the back surface 3b of the spatial light modulator 3. In the diffraction grating, the area P ₁ phase modulation amount is 0 (rad), and a region P ₂ phase modulation amount is [pi (rad) is a diagram showing a case where periodically alternating. It is a figure which shows the wavefront B2 which travels in the direction opposite to the wavefront B1. _{One unit PU is composed of three} regions P _{1 to} P 3, and in each of the plurality of unit PUs, the region P _{1 in} which the phase modulation amount is 0 (rad) and the phase modulation amount are 2π / 3 (rad). ) and region P ₂ is, how the phase modulation amount is arranged and the region P ₃ is 4 [pi] / 3 (rad) in this order is a diagram schematically showing. It is a graph which shows the relationship (where m = 1) of a period Λ and a diffraction angle θ when the period Λ of a diffraction grating is standardized by the wavelength λ. Part (a) shows a graph with a diffraction angle θ = 0 ° to 90 °, part (b) shows a magnified part of the diffraction angle θ = 5 ° to 30 °, and part (c) shows a diffraction angle θ. = The portion from 30 ° to 90 ° is enlarged and shown. It is a graph which shows the relationship (where m = 1) of the pitch L and the diffraction angle θ when the pitch L is standardized by the wavelength λ. Part (a) shows a graph with a diffraction angle θ = 0 ° to 70 °, and part (b) shows an enlarged portion of the pitch L = 0 to 2λ. 6 is a graph showing the relationship between pitch L and diffraction angle θ (where m = 1) when the wavelength λ = 532 nm. Part (a) shows a graph with a diffraction angle θ = 0 ° to 70 °, and part (b) shows an enlarged portion of the pitch L = 0 nm to 1000 nm. It is a figure which shows the relationship between the diffraction angle θ shown in FIG. 15 and the phase modulation amount of _{each region P 1 to} P _{3 in more detail.} It is a diagram showing the wave at a certain timing arising from the region P _2, the wavefront B3 generated by the waves at the preceding timing arising from the region P _1. Part (a) is a graph showing the relationship between the pitch L satisfying the mathematical formula (2) and the diffraction angle θ when the wavelength λ is 532 nm as an example. Part (b) is a graph showing an enlarged portion of the graph of part (a) where the pitch L is up to 2 μm. It is a graph which plotted the correlation between the phase difference between adjacent regions and m value. When the wavelength λ = 532 nm, the pitch L satisfying the equation (2) is obtained when the design diffraction angle θ is given, and further, the pitch L is substituted into the equation (5) to obtain the diffraction angle θ _B. It is a chart which shows the result. Part (a) is a graph showing the relationship between the pitch L satisfying the mathematical formula (2) and the diffraction angle θ when the wavelength λ is 467 nm. Part (b) is a graph showing an enlarged portion of the graph of part (a) where the pitch L is up to 2 μm. It is a graph which plotted the correlation between the phase difference between adjacent regions and m value. When the wavelength λ = 467 nm, the pitch L satisfying the equation (2) is obtained when the design diffraction angle θ is given, and further, the pitch L is substituted into the equation (5) to obtain the diffraction angle θ _B. It is a chart which shows the result. Part (a) is a graph showing the relationship between the pitch L satisfying the mathematical formula (2) and the diffraction angle θ when the wavelength λ is 630 nm. Part (b) is a graph showing an enlarged portion of the graph of part (a) where the pitch L is up to 2 μm. It is a graph which plotted the correlation between the phase difference between adjacent regions and m value. When the wavelength λ = 630 nm, the pitch L satisfying the equation (2) is obtained when the design diffraction angle θ is given, and further, the pitch L is substituted into the equation (5) to obtain the diffraction angle θ _B. It is a chart which shows the result. Part (a) is a diagram showing an example of a suitable diffraction grating based on the examination results. Part (b) is a partially enlarged view of part (a). It is a graph which conceptually shows the relationship between the phase modulation amount in a spatial light modulator 3 and the light intensity of the address light E2. Part (a) is a diagram showing a light-shielding pattern 80 of a light-shielding film (or a light-shielding plate). The part (b) and the part (c) are views showing an example of the planar shape of the light-shielding region 81. Part (d) is a plan view showing an example of a light-shielding film. The part (a) and the part (b) are diagrams conceptually showing a method of determining the amount of phase modulation in each region constituting the diffraction grating. The part (a) and the part (b) are diagrams conceptually showing a method of determining the amount of phase modulation in each region constituting the diffraction grating. Part (a) and part (b) are diagrams showing the configuration of the first modification. Part (a) is a side sectional view showing the configuration of the address light irradiation unit 4B as a second modification. (B) is a plan view of the light emitting device 41 and the optical member 44 included in the address light irradiation unit 4B. Part (a) is a side sectional view showing the configuration of the address light irradiation unit 4C as a third modification. Part (b) is a plan view of the light emitting device 46 included in the address light irradiation unit 4C. Part (c) is a diagram showing a cross section of the light emitting device 46 along the line I-I of part (b). Part (a) is a plan view showing another configuration of the light emitting device 46 as a third modification. Part (b) is a cross-sectional view taken along the line II-II of part (a). As a fourth modification, it is a figure which shows roughly the structure of the address light irradiation part 4D. Part (a) is a diagram schematically showing the configuration of the address light irradiation unit 4E as a fifth modification. Part (b) is a plan view of the light emitting device 49 as viewed from the axial direction of the annulus. The part (a), the part (b) and the part (c) are diagrams schematically showing another configuration of the fifth modification. As another configuration of the fifth modification, it is a figure which shows roughly the structure of the address light irradiation part 4F. Part (a) is a cross-sectional view showing the configuration of the surface emitting laser element array 50. Part (b) is an enlarged cross-sectional view showing the phase modulation layer 65A. It is a top view of the phase modulation layer 65A. It is a figure which shows the position of the center of gravity G of the different refractive index region in the XY plane. It is a figure for demonstrating the relationship between the optical image obtained by forming the output beam pattern of the surface emission laser element array 50, and the rotation angle distribution φ (x, y) in a phase modulation layer 65A. It is a figure for demonstrating the coordinate conversion from the spherical coordinate (r, θ _rot , θ _tilt ) to the coordinate (ξ, η, ζ) in the XYZ Cartesian coordinate system. Parts (a) and (b) are for explaining points to be noted when calculating using a general discrete Fourier transform (or fast Fourier transform) when determining the arrangement of each different refractive index region 65b. It is a figure. It is a figure which conceptually shows an example of the rotation angle distribution φ _{1 (x, y).} FIG. 3 is a plan view showing another configuration example of the phase modulation layer included in the S-iPM laser. It is a figure which shows the positional relationship of the different refractive index region 65b in a phase modulation layer 65B. As another example of the spatial light modulator, it is a top view which shows the structure of the reflection type dynamic metasurface (hereinafter, simply referred to as a metasurface) 7A. FIG. 52 is a cross-sectional view taken along the line III-III of FIG. 52, showing a cross-sectional structure of the metasurface 7A. As another configuration of the metasurface, it is sectional drawing which shows the metasurface 7B.

The image output device according to one embodiment has a main surface and a back surface, reflects light radiated to the main surface, and spatial light that modulates the phase of light for each of a plurality of pixels arranged in a two-dimensional manner. It includes a modulator, an image irradiation unit that irradiates a two-dimensional light image on the main surface, and an address light irradiation unit that irradiates an address light including a diffraction grating pattern on the back surface. Each pixel of the spatial light modulator has a configuration in which the phase modulation amount is changed according to the intensity of the address light applied to the back surface side of each pixel. The address light irradiation unit dynamically changes the direction of the diffraction grating pattern on the back surface. The image irradiation unit irradiates the main surface with a two-dimensional light image corresponding to the direction of the diffraction grating pattern.

In this image output device, the address light irradiation unit irradiates the back surface of the spatial light modulator with address light including a diffraction grating pattern. Since each pixel of the spatial light modulator has a configuration in which the phase modulation amount is changed according to the intensity of the address light applied to the back surface side of each pixel, the spatial light modulator has a phase pattern according to the diffraction grating pattern. Is given to the light incident on the main surface. Therefore, the two-dimensional light image irradiated from the image irradiation unit to the main surface is deflected in the direction corresponding to the direction of the diffraction grating pattern. Further, since the address light irradiation unit dynamically changes the direction of the diffraction grating pattern on the back surface, the deflection direction of the two-dimensional light image also dynamically changes. Then, since the image irradiation unit can irradiate the main surface with a two-dimensional light image corresponding to a desired direction of the diffraction grating pattern, it becomes possible to present a three-dimensional image to the observer. In addition, according to this image output device, a stereoscopic image is output by dynamically changing the address light including the diffraction grating pattern, so that the stereoscopic image can be produced while the spatial light modulator, which is an optical deflection element, is stationary. It becomes possible to output. Therefore, it is possible to easily increase the size of the spatial light modulator and enlarge the stereoscopic image as compared with the apparatus disclosed in Non-Patent Document 1 in which the holographic screen is mechanically rotated at high speed.

In the image output device, the address light irradiation unit may rotate the diffraction grating pattern on the back surface. In this case, it is possible to present a three-dimensional image in the entire circumferential direction of 360 °.

In the above image output device, the spatial light modulator includes a light reflecting layer located between the main surface and the back surface, a liquid crystal layer located between the light reflecting layer and the main surface, and a liquid crystal layer and the main surface. A light-transmitting first electrode layer located between the light-transmitting layers, an impedance-changing layer located between the light-reflecting layer and the back surface, and an impedance-changing layer that develops an impedance distribution according to the intensity distribution of address light, and an impedance-changing layer. It has a light-transmitting second electrode layer located between the back surface and the liquid crystal layer, and may have a partition wall for partitioning the liquid crystal for each pixel. When the address light is applied to the back surface of the spatial light modulator, the impedance distribution of the impedance changing layer becomes a distribution corresponding to the intensity distribution of the address light. When a voltage is applied between the first electrode layer and the second electrode layer, a strong electric field is applied to the liquid crystal layer in a pixel having a small impedance of the impedance changing layer. Further, in a pixel having a large impedance of the impedance changing layer, a weak electric field is applied to the liquid crystal layer, or no electric field is applied at all. Therefore, according to this image output device, it is possible to realize a configuration in which the phase modulation amount is changed according to the intensity of the address light radiated to the back surface side of each pixel in each pixel of the spatial light modulator. Further, by having the liquid crystal layer having a partition wall for partitioning the liquid crystal for each pixel, the interaction of the liquid crystal between the pixels can be reduced, and the phase pattern corresponding to the diffraction grating pattern can be made clearer.

In the above image output device, the partition walls extend in the first direction along the main surface and in the second direction along the main surface and orthogonal to the first direction, and the partition walls extend in the second direction. The pitch of may be larger than the pitch of the partition walls extending in the first direction. In this case, since the directions of the liquid crystals are easily aligned, the light transmission / non-transmission characteristics of the liquid crystal with respect to a specific polarization direction can be effectively exhibited.

In the above image output device, the pitch between the partition walls extending in the second direction may be twice or more the pitch between the partition walls extending in the first direction. According to the inventor's knowledge, in this case, since the directions of the liquid crystals are particularly easy to be aligned, the light transmission / non-transmission characteristics of the liquid crystal with respect to a specific polarization direction can be more effectively exhibited.

In the above image output device, the partition walls extend in the first direction along the main surface and in the second direction along the main surface and orthogonal to the first direction, and the partition walls extend in the first direction. And the pitch between the partition walls extending in the second direction may be 5 μm or less. By constructing the partition walls at such small intervals, the pixel size of the spatial light modulator can be reduced, and the period of the diffraction grating can be shortened. Therefore, the diffraction angle of the two-dimensional light image by the spatial light modulator can be increased so that the output direction of the stereoscopic image can be brought closer to the plane including the main surface of the spatial light modulator, so that the three-dimensional image can be obtained in a wide angle range. It can be observed and can provide a practical stereoscopic image to an observer existing around the spatial light modulator.

In the above image output device, the impedance changing layer may include at least one of hydrogenated amorphous silicon, a GaN-based compound, an InP-based compound, and a GaAs-based compound. The impedance of these substances changes when exposed to light. Therefore, in this case, it is possible to preferably realize an impedance changing layer that expresses an impedance distribution according to the intensity distribution of the address light.

In the above image output device, the spatial light modulator has a transparent conductive layer and a dielectric layer, and is provided on one surface of the laminated structure and a laminated structure in which a two-dimensional optical image is input to one surface. A first metal film formed and a second metal film provided on the other surface of the laminated structure facing one surface and reflecting a two-dimensional optical image input to the laminated structure toward one surface. , An impedance changing layer provided at a position sandwiching the second metal film between the laminated structure and expressing an impedance distribution according to the intensity distribution of the address light, and an impedance changing layer between the second metal film. A light-transmitting electrode layer provided at a sandwiching position may be provided. Then, in each of the plurality of pixels, the laminated structure includes a pair of portions provided at a pair of positions sandwiching the first metal film when viewed from the stacking direction and exposed from the first metal film, and includes the first metal film and the first metal film. The two metal films may include a plurality of partially metal films provided for each pixel and separated from each other.

When the address light is applied to the back surface of the spatial light modulator, the impedance distribution of the impedance changing layer becomes a distribution corresponding to the intensity distribution of the address light. When a voltage is applied between the first metal film and the electrode layer, a strong electric field is applied between the first metal film and the second metal film in a pixel having a small impedance of the impedance changing layer. Further, in a pixel having a large impedance of the impedance changing layer, a weak electric field is applied between the first metal film and the second metal film, or no electric field is applied at all. Further, in this image output device, the laminated structure includes a pair of portions. The pair of portions are provided at a pair of positions sandwiching the first metal film when viewed from the stacking direction, and are exposed from the first metal film. The light input to one of the pair of portions is guided between the first metal film and the second metal film, and is output from the other of the pair of portions to the outside. If the width of the first metal film and the thickness of the laminated structure are sufficiently smaller than the wavelength of light, when an electric field is applied between the first metal film and the second metal film, a gap surface plasmon will occur. Induced currents in opposite directions called modes are generated in each of the first metal film and the second metal film, and strong magnetic resonance (plasmon resonance) is generated in the laminated structure. By utilizing this magnetic resonance, the phase of light passing between the first metal film and the second metal film can be modulated. Here, when an electric field is applied between the first metal film and the second metal film, the electron density near the interface between the transparent conductive layer contained in the laminated structure and the dielectric layer increases. As a result, the portion of the transparent conductive layer near the interface is effectively metallized, and the effective refractive index of the laminated structure changes significantly. Since the amount of modulation in the above-mentioned phase modulation depends on the effective refractive index of the laminated structure, the effective refractive index is controlled by changing the electric field between the first metal film and the second metal film, and thus the output light. Phase can be controlled. Therefore, according to this image output device, it is possible to realize a configuration in which the phase modulation amount is changed according to the intensity of the address light radiated to the back surface side of each pixel in each pixel of the spatial light modulator.

In the above image output device, the address light irradiation unit includes a light emitting unit that outputs address light including a diffraction grating pattern, and a driving unit that dynamically changes the posture angle around the optical axis of the light emitting unit. It is also good. In this case, it is possible to preferably realize an address light irradiation unit that dynamically changes the direction of the diffraction grating pattern on the back surface.

In the above image output device, the address light irradiation units are arranged side by side along the circumference, and optical a plurality of light emitting units capable of outputting address light including a diffraction grating pattern, and a plurality of light emitting units and the back surface thereof. You may input the address light from a part of the light emitting part corresponding to the direction of the diffraction grating pattern selected from a plurality of light emitting parts with the optical system to be coupled to the back surface. Further, in this case, since the optical system includes a metal lens, it is possible to realize a large-area and thin optical system, and it is possible to irradiate the back surface of the spatial light modulator with address light having a relatively large spread.

In the above image output device, the address light irradiation unit is provided along the circumference and has a light emitting unit that outputs address light including a diffraction grating pattern whose periodic direction is the radial direction of the circumference. , A plurality of element electrodes arranged side by side in the circumferential direction of the circumference and selectively emitting address light in a portion corresponding to the direction of the diffraction grating pattern may be included. In this case, it is possible to preferably realize an address light irradiation unit that dynamically changes the direction of the diffraction grating pattern on the back surface.

In the above image output device, the light emitting unit may include a plurality of light emitting regions arranged based on the diffraction grating pattern. Alternatively, the light emitting unit includes a surface emitting laser element having an active layer and a phase modulation layer, and the phase modulation layer has a refractive index different from that of the basic layer and is perpendicular to the thickness direction of the phase modulation layer. When a virtual square grid is set in the plane of the phase modulation layer, which includes a plurality of different refractive index regions distributed in a two-dimensional manner, the center of gravity of the plurality of different refractive index regions is the virtual square grid. It is arranged away from the grid points, and the rotation angle around the grid points is set individually for each different refractive index region, or the center of gravity of multiple different refractive index regions is a virtual square grid grid. It may be arranged on a straight line that passes through the points and is inclined with respect to the square grid, and the distance between the center of gravity of each different refractive index region and the corresponding grid points may be set individually for each different refractive index region. With any of these, a light emitting unit that outputs address light including a diffraction grating pattern can be suitably realized.

In the above image output device, the light emitting unit is provided on the light emitting surface of the photonic crystal surface emitting laser element having the active layer and the photonic crystal layer and the light emitting surface of the photonic crystal surface emitting laser element, and corresponds to the diffraction grating pattern. It may have a periodic structure in which the opening and the light-shielding portion are periodically repeated. In this case, a light emitting unit that outputs address light including a diffraction grating pattern can be preferably realized.

In the above image output device, the address light irradiation unit interferes with the laser light source, the branch portion that branches the laser light output from the laser light source, and one laser light branched by the branch portion and the other laser light. It has an interference optical system that causes interference fringes to be generated, and the interference optical system includes a position change portion that dynamically changes the relative positional relationship at the time of interference between one laser beam and the other laser beam. The interference fringes may be used as a diffraction grid pattern. The interference fringes can be used as a diffraction grating pattern. Further, by dynamically changing the relative positional relationship between one laser beam and the other laser beam at the time of interference, the direction of the interference fringes, that is, the direction of the diffraction grating pattern can be dynamically changed. Therefore, in this case, the address light irradiation unit can be suitably realized.

In the above image output device, the diffraction grating pattern has a configuration in which the light intensity changes periodically in a certain direction, and the light intensity gradually and monotonically increases or decreases in each period. The number of regions in which the light intensities differ from each other in the cycle may be 3 or more. In this case, it is possible to reduce the deflection of the two-dimensional optical image in the direction opposite to the desired deflection direction and output the stereoscopic image more clearly.

In the above image output device, it is arranged between the image irradiation unit and the spatial light modulator, and reduces the intensity of at least a part of the wavelength components other than visible light contained in the two-dimensional light image. Further filters may be provided. As a result, the degree to which the light of the two-dimensional light image from the image irradiation unit affects the phase modulation amount of the spatial light modulator can be reduced.

Hereinafter, specific examples of the image output device of the present disclosure will be described with reference to the drawings. It should be noted that the present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. In the following description, the same elements will be designated by the same reference numerals in the description of the drawings, and duplicate description will be omitted. In the following description, having light transmission means transmitting light having a wavelength to be transmitted by 50% or more.

(First Embodiment)
FIG. 1 is a perspective view schematically showing the overall configuration of the image output device 1A according to the first embodiment. FIG. 2 is a cross-sectional view of the image output device 1A. The image output device 1A is a device that simulates a three-dimensional (three-dimensional) image to the observer A on the side of the image output device 1A. As shown in FIGS. 1 and 2, the image output device 1A includes a high-speed projector 2A, a spatial light modulator 3, and an address light irradiation unit 4A. The spatial light modulator 3 is a plate-shaped device having a main surface (upper surface) 3a and a back surface (lower surface) 3b located on the opposite side of the main surface 3a. The main surface 3a and the back surface 3b are flat and parallel to each other, and in one example, their normal directions are along the vertical direction. The high-speed projector 2A is arranged above the spatial light modulator 3 so as to face the main surface 3a. The address light irradiation unit 4A is arranged below the spatial light modulator 3 so as to face the back surface 3b.

The high-speed projector 2A is an example of the image irradiation unit in the present embodiment, and irradiates the main surface 3a of the spatial light modulator 3 with light E1 including a two-dimensional light image. The incident direction of the light E1 with respect to the main surface 3a coincides with the normal direction of the main surface 3a. The high-speed projector 2A may output light E1 having a single wavelength, or may output light E1 containing a plurality of wavelength components. The single or multiple wavelength components of light E1 are included in the visible light region. In one example, the plurality of wavelength components are a green component, a blue component, and a red component. The high-speed projector 2A can be suitably configured by, for example, a DLP (Digital Light Processing) projector using a DMD (Digital Micromirror Device). The frame rate of the high-speed projector 2A is, for example, 1 k frames or more per second and 100 k frames or less per second. This frame rate may be set to a suitable value according to the rotation speed of the diffraction grating pattern output from the address light irradiation unit 4A described later.

As shown in FIG. 2, a filter 15 and a lens 16 are provided side by side on the optical path between the high-speed projector 2A and the spatial light modulator 3. The filter 15 is a wavelength filter that reduces (or removes) the intensity of at least a part of the wavelength components other than visible light contained in the light E1. In one example, the filter 15 is a bandpass filter that reduces (or removes) the intensity of all other wavelength components contained in the light E1 except visible light. The filter 15 may have a reducing (or removing) action on other wavelength ranges excluding an arbitrary wavelength range including a wavelength component contained in the light E1. In this case, the visible region may be included in other wavelength regions. The lens 16 is an imaging lens that forms an image of light E1 on the retina of the eye Aa of the observer A. In the illustrated example, the filter 15 is arranged between the high-speed projector 2A and the lens 16, but the lens 16 may be arranged between the high-speed projector 2A and the filter 15.

The spatial light modulator 3 reflects the light E1 including the two-dimensional light image irradiated on the main surface 3a, and modulates the phase of the light E1 for each of a plurality of pixels arranged in a two-dimensional manner. Each pixel of the spatial light modulator 3 has a configuration in which the phase modulation amount is changed according to the intensity of each pixel of the address light E2 irradiated from the back surface 3b side. FIG. 3 is a cross-sectional view of the spatial light modulator 3, showing a cross section intersecting the main surface 3a and the back surface 3b. As shown in FIG. 3, the spatial light modulator 3 includes a transparent substrate 31, a transparent electrode layer 32, an impedance change layer 33, a dielectric mirror 34, a liquid crystal alignment film 35, a liquid crystal layer 36, a transparent electrode layer 37, and a transparent substrate. Has 38.

The transparent substrate 31 is a plate-shaped member having light transmission. The term "light transmission" as used herein means a property of transmitting address light E2 (see FIG. 2), which will be described later. In one example, the transparent substrate 31 is a glass substrate. The transparent substrate 31 includes a main surface 31a and a back surface 31b that are parallel to each other and face in opposite directions. The main surface 31a and the back surface 31b are flat and smooth. The back surface 31b coincides with the back surface 3b of the spatial light modulator 3. The thickness of the transparent substrate 31 is, for example, 20 μm or more and 1 mm or less.

The transparent electrode layer 32 is an example of the second electrode layer in the present embodiment, and is located between the impedance changing layer 33 and the back surface 3b. In the illustrated example, the transparent electrode layer 32 is in contact with the main surface 31a of the transparent substrate 31. The transparent electrode layer 32 has light transmission like the transparent substrate 31. That is, the transparent electrode layer 32 transmits the address light E2 (see FIG. 2) described later. The constituent material of the transparent electrode layer 32 is, for example, at least one of indium tin oxide (ITO) and zinc oxide-based conductive material (aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO)). include. The thickness of the transparent electrode layer 32 is, for example, 1 nm or more and 1 μm or less. The transparent electrode layer 32 is divided for each pixel, and the transparent electrode layer 32 of each pixel is separated from each other with a gap (slit) GA interposed therebetween.

The impedance change layer 33 is a semiconductor layer located between the dielectric mirror 34 and the back surface 3b. In the illustrated example, the impedance changing layer 33 is located between the dielectric mirror 34 and the transparent electrode layer 32. The impedance change layer 33 expresses an impedance distribution according to the intensity distribution of the address light E2 (see FIG. 2). Specifically, the impedance of the material constituting the impedance change layer 33 changes monotonically according to the light intensity when it receives light. Examples of such a material include hydrogenated amorphous silicon, GaN-based compounds, InP-based compounds, and GaAs-based compounds. Therefore, the impedance change layer 33 of the present embodiment is at least one of hydrogenated amorphous silicon, a GaN-based compound (for example, i-type GaN), an InP-based compound (for example, i-type InP), and a GaAs-based compound (for example, i-type GaAs). It may be configured to include one. The constituent material of the impedance changing layer 33 is not limited to these, and may be, for example, a semiconductor material having photoconductivity. The wavelength of the address light E2 is, for example, 400 nm or more and 2 μm or less. If the address light E2 is infrared light, even if the address light E2 leaks to the main surface 3a, it is not visible to the observer A and does not become noise light, which is preferable. The thickness of the impedance changing layer 33 is, for example, 10 nm or more and 20 μm or less. The impedance change layer 33 is divided for each pixel, and the impedance change layer 33 of each pixel is separated from each other with a gap GA interposed therebetween.

The dielectric mirror 34 is an example of the light reflecting layer in the present embodiment, and reflects the light E1 irradiated on the main surface 3a. The dielectric mirror 34 is located between the main surface 3a and the back surface 3b, and as a specific example, is located between the impedance changing layer 33 and the liquid crystal layer 36. In the illustrated example, the dielectric mirror 34 is in contact with the impedance changing layer 33. The dielectric mirror 34 is formed by alternately laminating a high refractive index dielectric layer and a low refractive index dielectric layer having a relatively low refractive index with respect to the high refractive index dielectric layer. The high refractive index dielectric layer contains, for example, at least one of _{Ta 2} O ₅ , TIO ₂ , Nb ₂ O ₅ , SiN, Al ₂ O ₃ , and HfO _2. Further, the low refractive index dielectric layer contains, for example, at least one of _{SiO 2} and Mg F _2. The dielectric mirror 34 is divided into pixels, and the dielectric mirrors 34 of each pixel are separated from each other with a gap GA interposed therebetween.

The liquid crystal alignment film 35 is a parallel alignment type, is provided on the dielectric mirror 34, and is in contact with the dielectric mirror 34 in one example. The liquid crystal alignment film 35 may be configured to include, for example, a polycarbonate film and an alignment film provided on the polycarbonate film (for example, AL-1254 of JSR Corporation). The liquid crystal alignment film 35 is divided into pixels, and the liquid crystal alignment film 35 of each pixel is separated from each other with a gap GA interposed therebetween.

The liquid crystal layer 36 is located between the dielectric mirror 34 and the main surface 3a, and as a specific example, is located between the dielectric mirror 34 and the transparent electrode layer 37. In one example, the liquid crystal layer 36 includes a nematic liquid crystal 36a. Further, the liquid crystal layer 36 has a partition wall 39a that partitions the nematic liquid crystal 36a for each pixel. The partition wall 39a is made of resin, for example. Alternatively, the partition wall 39a may be made of a semiconductor material such as Si or an inorganic material such as _{SiO 2 or SiN.} Part (a) of FIG. 4 is a partially enlarged plan view of the partition wall 39a. Part (b) of FIG. 4 is a partially enlarged perspective view of the partition wall 39a, and shows the structure in the vicinity of the partition wall 39a upside down. As shown in FIG. 4, the partition wall 39a of the present embodiment has a planar shape such as a grid shape, and divides the liquid crystal into a rectangular shape when viewed from the thickness direction of the liquid crystal layer 36. Not limited to this example, the partition wall 39a may partition the liquid crystal display into a square shape. Further, the partition wall 39a is integrally configured with the layer 39b provided on the liquid crystal layer 36. The partition wall 39a and the liquid crystal alignment film 35 are joined to each other via a spacer 301 surrounding the liquid crystal layer 36. Spacer 301 is a resin adhesive containing dispersed beads. The diameter of the dispersed beads is larger than the height h of the partition wall 39a, and is, for example, about several μm in diameter. As a result, a gap through which the liquid crystal can pass is formed between the liquid crystal alignment film 35 and the partition wall 39a. The height h of the partition wall 39a is, for example, 1 μm. The width w of the partition wall 39a is, for example, 0.17 μm or more and 0.2 μm or less.

As shown in the portion (a) of FIG. 4, the partition wall 39a has a portion extending in the first direction D1 along the main surface 3a and intersecting the first direction D1 along the main surface 3a (for example, orthogonally). Includes a portion extending in the second direction D2. The pitch (center spacing) d1 between the portions extending in the second direction D2 is larger than the pitch d2 between the portions extending in the first direction D1. Therefore, the planar shape of one space (pixel) partitioned by the partition wall 39a is a rectangle with the first direction D1 as the longitudinal direction. The pitch d1 may be twice or more the pitch d2, and in one embodiment, the pitch d1 is twice the pitch d2. Further, the pitches d1 and d2 may both be 5 μm or less, and in one embodiment, the pitch d1 is 1 μm and the pitch d2 is 0.5 μm.

See FIG. 3 again. The transparent electrode layer 37 is an example of the first electrode layer in the present embodiment, and is located between the liquid crystal layer 36 and the main surface 3a. In the illustrated example, the transparent electrode layer 37 is in contact with the surface of the layer 39b integrated with the partition wall 39a on the side opposite to the partition wall 39a. The transparent electrode layer 37 has light transmission. The term "light transmission" as used herein means a property of transmitting light E1 (see FIG. 2) including a two-dimensional light image emitted from the high-speed projector 2A. In one example, the transparent electrode layer 37 transmits a wavelength band including a visible light region. The constituent material of the transparent electrode layer 37 includes, for example, ITO, at least one of zinc oxide-based conductive materials (AZO, GZO). The thickness of the transparent electrode layer 37 is, for example, 1 nm or more and 1 μm or less. Unlike the transparent electrode layer 32, the transparent electrode layer 37 is not divided for each pixel, but is integrally provided over a plurality of pixels.

The transparent substrate 38 is a plate-shaped member having light transmission like the transparent electrode layer 37. That is, the transparent substrate 38 transmits the light E1 (see FIG. 2) including the two-dimensional light image emitted from the high-speed projector 2A. In one example, the transparent substrate 38 is a glass substrate. The transparent substrate 38 includes a main surface 38a and a back surface 38b that are parallel to each other and face in opposite directions. The main surface 38a and the back surface 38b are flat and smooth. The main surface 38a coincides with the main surface 3a of the spatial light modulator 3. The back surface 38b faces the transparent electrode layer 37 and is in contact with, for example, the transparent electrode layer 37. The thickness of the transparent substrate 38 is, for example, 20 μm or more and 1 mm or less.

The operation of the spatial light modulator 3 is as follows. First, an AC voltage source 11 (see FIG. 2) is connected between the transparent electrode layer 32 and the transparent electrode layer 37, and an AC voltage is applied. The effective voltage of the AC voltage is, for example, 3 volts, and the frequency is, for example, in the range of 10 Hz to 100 Hz. When the address light E2 is irradiated on the back surface 3b side, the address light E2 reaches the impedance changing layer 33 and gives an impedance distribution to the impedance changing layer 33. That is, the impedance of the impedance changing layer 33 is maintained in a state of being large in the pixel where the light intensity of the address light E2 is low, and the impedance of the impedance changing layer 33 is small in the pixel where the light intensity of the address light E2 is high. Therefore, the impedance distribution of the impedance changing layer 33 becomes a distribution corresponding to the intensity distribution of the address light E2. In the pixel in which the impedance of the impedance changing layer 33 becomes small, the voltage applied to the liquid crystal layer 36 becomes large, and a strong electric field is applied to the liquid crystal layer 36. Further, in the pixel in which the impedance of the impedance changing layer 33 is maintained in a large state, the impedance of the impedance changing layer 33 is larger than the impedance of the liquid crystal layer 36, so that the voltage applied to the liquid crystal layer 36 is small and the liquid crystal layer 36 has a small voltage. A weak electric field is applied (or no electric field is applied at all). The address light E2 is blocked by the dielectric mirror 34 and does not reach the liquid crystal layer 36.

The main surface 3a is irradiated with light E1 including a two-dimensional light image from the high-speed projector 2A. The light E1 passes through the transparent substrate 38, the transparent electrode layer 37, and the liquid crystal layer 36, is reflected by the dielectric mirror 34, passes through the liquid crystal layer 36, the transparent electrode layer 37, and the transparent substrate 38 again, and is transmitted from the main surface 3a. It emits light to the outside of the spatial light modulator 3. In the liquid crystal layer 36, when an electric field is applied, the liquid crystal molecules of the nematic liquid crystal 36a are tilted. The slope of the liquid crystal molecules depends on the magnitude of the applied electric field. As the liquid crystal molecules are tilted, the equivalent refractive index of the nematic liquid crystal 36a with respect to the light E1 becomes smaller, and the phase of the light E1 advances in the nematic liquid crystal 36a. Therefore, a phase distribution corresponding to the light intensity distribution of the address light E2 is given to the light E1. In the spatial light modulator 3, the response time required for phase modulation of π (rad) is, for example, about 30 milliseconds, and in that case, it is possible to realize a pattern change of 30 frames per second.

Here, an example of a method for manufacturing the spatial light modulator 3 will be described. 5 and 6 are cross-sectional views showing each step in the method of manufacturing the spatial light modulator 3. First, as shown in part (a) of FIG. 5, a transparent substrate 38 is prepared, and a transparent electrode layer 37 is formed on one surface of the transparent substrate 38. The method for forming the transparent electrode layer 37 is, for example, a vacuum vapor deposition method or sputtering. Next, as shown in part (b) of FIG. 5, the ultraviolet curable resin 39 for the partition wall 39a is applied onto the surface of the transparent electrode layer 37 on the side opposite to the transparent substrate 38. Then, as shown in the portion (c) of FIG. 5, a mold 51 having a grid-like groove corresponding to the partition wall 39a is pressed against the ultraviolet curable resin 39 (nanoimprint), and the ultraviolet curable resin 39 is ultraviolet while maintaining the state. The ultraviolet curable resin 39 is cured by irradiating it with light. After that, the mold 51 is removed. As a result, the partition wall 39a and the layer 39b are formed as shown in the portion (d) of FIG.

Further, as shown in the portion (a) of FIG. 6, the transparent substrate 31 is prepared, and the transparent electrode layer 32 is formed on one surface of the transparent substrate 31. The method for forming the transparent electrode layer 32 is, for example, a vacuum vapor deposition method or sputtering. Next, the impedance change layer 33 is formed on the transparent electrode layer 32. The method for forming the impedance changing layer 33 is, for example, a vacuum vapor deposition method or sputtering. After that, as shown in the part (b) of FIG. 6, the dielectric mirror 34 is formed on the impedance changing layer 33. That is, the dielectric mirror 34 is formed by alternately stacking the high refractive index dielectric layer and the low refractive index dielectric layer having a relatively low refractive index with respect to the high refractive index dielectric layer. The method for forming the high refractive index dielectric layer and the low refractive index dielectric layer is, for example, a vacuum vapor deposition method or sputtering. Then, as shown in the portion (c) of FIG. 6, the liquid crystal alignment film 35 is arranged on the dielectric mirror 34. Specifically, the polycarbonate film and the alignment film are laminated.

Subsequently, an adhesive containing dispersed beads was applied to the periphery of the region filled with the liquid crystal on the liquid crystal alignment film 35, and the partition wall 39a shown in the portion (d) of FIG. 5 and the portion (c) of FIG. 6 were covered with the adhesive. The liquid crystal alignment film 35 shown is bonded to each other (part (d) in FIG. 6). At this time, the diameter of the dispersed beads is made larger than the height of the partition wall 39a, and a gap through which the nematic liquid crystal 36a can pass is provided between the partition wall 39a and the liquid crystal alignment film 35. In addition, no adhesive is applied to the opening for filling the liquid crystal display. After the adhesive is cured, the pressure is reduced as a whole, nematic liquid crystal 36a is injected through the opening for filling the liquid crystal, and then the adhesive is applied to the opening to seal the opening. In this way, the spatial light modulator 3 is completed.

See FIG. 2 again. The address light irradiation unit 4A irradiates the back surface 3b of the spatial light modulator 3 with the address light E2 including the diffraction grating pattern. The address light irradiation unit 4A of the present embodiment has an annular light emitting device 41 and an optical system 43 arranged inside the light emitting device 41. FIG. 7 is a plan view of the light emitting device 41 as viewed from the axial direction of the annulus. As shown in FIG. 7, the light emitting device 41 includes a plurality of light emitting units 42 arranged based on the diffraction grating pattern. The plurality of light emitting units 42 are arranged side by side along the circumference with the light emitting surface 42a facing inward. FIG. 8 is a front view showing a light emitting surface 42a of one light emitting unit 42. As shown in FIG. 8, each light emitting unit 42 has light emitting regions 42b and 42c arranged periodically and alternately in the vertical direction on the light emitting surface 42a based on the diffraction grating pattern. By having such light emitting regions 42b and 42c, each light emitting unit 42 can output the address light E2 including the diffraction grating pattern described later in the near field image. The light emitting regions 42b and 42c have a periodic structure (for example,) in which an opening and a light shielding portion are periodically repeated on the light emitting surface of a surface emitting semiconductor light emitting device such as a light emitting diode or a surface emitting laser according to a diffraction grating pattern. , See FIG. 38, which will be described later). The surface emitting laser is a vertical cavity surface emitting laser (VCSEL), a photonic crystal surface emitting laser (PCSEL) having an active layer and a photonic crystal layer, or S-iPM. It may be a laser (described later).

As shown in FIG. 2, the optical system 43 optically couples a plurality of light emitting units 42 and the back surface 3b of the spatial light modulator 3. Then, the optical system 43 deflects the address light E2 emitted from the light emitting regions 42b and 42c of each light emitting unit 42 toward the back surface 3b of the spatial light modulator 3. The optical system 43 exhibits an annular shape concentric with the light emitting device 41, and the shape of the optical system 43 in the cross section including the central axis of the annulus includes, for example, an Off-axis type convex lens. Alternatively, the shape of the optical system 43 in the cross section including the central axis of the annulus may include a metal lens. When the optical system 43 includes a metal lens, the thickness of the optical system 43 in the radial direction can be reduced, which is suitable for a dense arrangement. As a result, when a convex lens having a large radius of curvature comes into contact with each other, the convex lens can be replaced with a metal lens which is a flat lens, and the deflection angle can be further increased. The shape of the optical system 43 is not limited to these, and various other shapes can be adopted as long as the address light E2 can be deflected toward the back surface 3b.

9 to 12 are diagrams conceptually showing how the address light E2 is irradiated to the back surface 3b of the spatial light modulator 3. In these figures, the intensity distribution of the address light E2 is represented by shades of color. The darker the color, the lower the light intensity, and the lighter the color, the higher the light intensity. The address light E2 of the present embodiment includes a region E2a having a low light intensity (or a region having substantially zero light intensity), a region E2b having a slightly high light intensity, and a region E2c having a high light intensity, and these three regions are included. A diffraction grating pattern is formed by repeatedly arranging E2a to E2c in order. In other words, the diffraction grating pattern has a structure in which the light intensity changes periodically in a certain direction, and the light intensity gradually increases or decreases gradually (that is, monotonously) within each period, and within each period. The number of regions in which the light intensities differ from each other is 3 or more (3 in the illustrated example). As shown in FIG. 9, the arrangement period of the regions E2a to E2c coincides with or is larger than three times the pixel pitch in the longitudinal direction of each pixel 30. Then, as shown in FIGS. 9 to 12, the direction of the diffraction grating pattern on the back surface 3b (the diffraction grating pattern included in the address light E2 irradiated on the back surface 3b) is dynamically changed. For example, the direction of the diffraction grating pattern on the back surface 3b is rotated around the center of the back surface 3b. Such a change in the orientation of the diffraction grating pattern is preferable by outputting the address light E2 from a part of the light emitting units 42 corresponding to the desired orientation of the diffraction grating pattern selected from the plurality of light emitting units 42. Can be realized. The rotation speed of the diffraction grating pattern is, for example, 10 rpm or more and 10000 rpm or less, and in one example, 3600 rpm.

The effect obtained by the image output device 1A of the present embodiment having the above configuration will be described. In the image output device 1A, the address light irradiation unit 4A irradiates the back surface 3b of the spatial light modulator 3 with the address light E2 including the diffraction grating pattern. Since each pixel 30 of the spatial light modulator 3 has a configuration in which the phase modulation amount is changed according to the intensity of the address light E2 irradiated on the back surface 3b side of each pixel 30, the spatial light modulator 3 has a diffraction grating. A phase pattern corresponding to the pattern is given to the light E1 incident on the main surface 3a. Therefore, when the two-dimensional light image emitted from the high-speed projector 2A onto the main surface 3a is reflected by the spatial light modulator 3, it is output deflected in a direction corresponding to the direction of the diffraction grating pattern. Further, since the address light irradiation unit 4A dynamically changes the direction of the diffraction grating pattern on the back surface 3b, the deflection direction of the two-dimensional light image also dynamically changes. When the high-speed projector 2A irradiates the main surface 3a with a two-dimensional light image corresponding to the orientation of the diffraction grating pattern, it becomes possible to present a three-dimensional image to the observer A. In addition, according to this image output device 1A, a stereoscopic image is output by dynamically changing the address light E2 including the diffraction grating pattern, so that the spatial light modulator 3 which is an optical deflection element remains stationary. It becomes possible to output a stereoscopic image. Therefore, it is possible to easily increase the size of the spatial light modulator 3 and enlarge the stereoscopic image as compared with the apparatus disclosed in Non-Patent Document 1 in which the holographic screen is mechanically rotated at high speed.

As in the present embodiment, the address light irradiation unit 4A may rotate the diffraction grating pattern on the back surface 3b of the spatial light modulator 3. In this case, it is possible to present a three-dimensional image in the entire circumferential direction of 360 °. The dynamic change in the orientation of the diffraction grating pattern is not limited to the rotation of the diffraction grating pattern, and may be a rotation operation in a limited angle range.

As in the present embodiment, the spatial light modulator 3 includes a dielectric mirror 34 located between the main surface 3a and the back surface 3b, and a liquid crystal layer 36 located between the dielectric mirror 34 and the main surface 3a. An impedance that is located between the transparent electrode layer 37 located between the liquid crystal layer 36 and the main surface 3a and between the dielectric mirror 34 and the back surface 3b and exhibits an impedance distribution according to the intensity distribution of the address light E2. The change layer 33 may have a transparent electrode layer 32 located between the impedance change layer 33 and the back surface 3b. The liquid crystal layer 36 may have a partition wall 39a that partitions the nematic liquid crystal 36a for each pixel. When the address light E2 is applied to the back surface 3b of the spatial light modulator 3, the impedance distribution of the impedance changing layer 33 becomes a distribution corresponding to the intensity distribution of the address light E2. When a voltage is applied between the transparent electrode layer 37 and the transparent electrode layer 32, a strong electric field is applied to the liquid crystal layer 36 in pixels having a small impedance of the impedance changing layer 33. Further, in a pixel having a large impedance of the impedance changing layer 33, a weak electric field is applied to the liquid crystal layer 36. Therefore, according to this image output device 1A, in each pixel of the spatial light modulator 3, it is possible to realize a configuration in which the phase modulation amount is changed according to the intensity of the address light E2 irradiated on the back surface 3b side of each pixel. Can be done. Further, by having the partition wall 39a for partitioning the nematic liquid crystal 36a for each pixel, the interaction of the nematic liquid crystal 36a between the pixels can be reduced, and the phase pattern corresponding to the diffraction grating pattern can be made clearer. can.

As in the present embodiment, the partition wall 39a extends in the first direction D1 and the second direction D2 along the main surface 3a, and the pitch between the partition walls 39a extending in the second direction D2 is the first direction. It may be larger than the pitch between the partition walls 39a extending to D1. In this case, since the directions of the nematic liquid crystal 36a are easily aligned, the light transmission / non-transmission characteristics of the nematic liquid crystal 36a with respect to a specific polarization direction can be effectively exhibited.

As in the present embodiment, the pitch between the partition walls 39a extending in the second direction D2 may be twice or more the pitch between the partition walls 39a extending in the first direction D1. According to the inventor's knowledge, in this case, the orientation of the nematic liquid crystal 36a is particularly easy to align, so that the light transmission / non-transmission characteristics of the nematic liquid crystal 36a with respect to a specific polarization direction can be more effectively exhibited.

As in the present embodiment, the pitch between the partition walls 39a extending in the first direction D1 and the pitch between the partition walls 39a extending in the second direction D2 may be 5 μm or less. By forming the partition walls 39a at such small intervals, the pixel size of the spatial light modulator 3 can be reduced, and the period of the diffraction grating can be shortened. Therefore, as will be described later, the diffraction angle of the two-dimensional light image by the spatial light modulator 3 can be increased so that the output direction of the stereoscopic image can be brought closer to the plane including the main surface 3a of the spatial light modulator 3. It is possible to provide a practical stereoscopic image to the observer A existing around the spatial light modulator 3.

As in the present embodiment, the impedance change layer 33 may include at least one of hydrogenated amorphous silicon, a GaN-based compound, an InP-based compound, and a GaAs-based compound. The impedance of these substances changes when exposed to light. Therefore, in this case, the impedance change layer 33 that expresses the impedance distribution according to the intensity distribution of the address light E2 can be suitably realized.

As in the present embodiment, the address light irradiation units 4A are arranged side by side along the circumference, and a plurality of light emitting units 42 capable of outputting address light E2 including a diffraction grating pattern, and a plurality of light emitting units 42. It may have an optical system 43 that optically couples the back surface 3b. Then, a part of the light emitting units 42 corresponding to the desired direction of the diffraction grating pattern selected from the plurality of light emitting units 42 may output the address light E2. In this case, the mechanical drive unit can be eliminated, which leads to improvement in reliability. Further, in this case, since the optical system 43 includes the metal lens, it is possible to realize a large area and thin optical system 43, and it is possible to irradiate the back surface 3b of the spatial light modulator 3 with the address light E2 having a relatively large spread. can.

As in the present embodiment, the image output device 1A is arranged between the high-speed projector 2A and the spatial light modulator 3, and at least a part of other wavelength components other than visible light contained in the two-dimensional light image. The filter 15 may be provided to reduce the intensity of the wavelength component of. As a result, the amount of incident light of the light E1 on the impedance changing layer 33 can be reduced, and the degree to which the light E1 affects the phase modulation amount of the spatial light modulator 3 can be reduced.

As in the present embodiment, the transparent electrode layer 32, the impedance change layer 33, the dielectric mirror 34, and the liquid crystal alignment film 35 are divided into pixels, and each pixel portion is separated from each other with a gap GA interposed therebetween. good. In this case, crosstalk between adjacent pixels can be reduced.

As described above, the light emitting unit 42 is provided on the light emitting surface of the PCSEL having the active layer and the photonic crystal layer and the light emitting surface of the PCSEL, and has a periodic structure in which the opening and the light shielding unit are periodically repeated according to the diffraction grating pattern. And may have. In this case, the light emitting unit 42 that outputs the address light including the diffraction grating pattern can be suitably realized.

なお、回折角θとは、二次元光像の入射方向である法線方向Ｄａと、波面の法線方向すなわち光出射方向Ｄｂとのなす角であって、主面３ａと波面Ｂ１とのなす角に等しい。例えば回折角θを３０°としたい場合、Ｌ＝λとするとよい。 Here, the diffraction grating realized in the spatial light modulator 3 will be described in detail. Figure 13 is a region P ₁ phase modulation amount is 0 (rad), and a region P ₂ phase modulation amount is [pi (rad) indicates the case where are arranged regularly alternately. The straight line B1 in the figure shows the wavefront when the two-dimensional optical image irradiated from the normal direction of the main surface 3a is diffracted by this diffraction grating. In this example, the relationship between the diffraction angle θ, the wavelength λ of the two-dimensional optical image, and _{the array pitch L of the regions P 1} and P ₂ is expressed by the following equation (1).

The diffraction angle θ is an angle formed by the normal direction Da, which is the incident direction of the two-dimensional light image, and the normal direction of the wave surface, that is, the light emission direction Db, and is formed by the main surface 3a and the wave surface B1. Equal to a corner. For example, when it is desired to set the diffraction angle θ to 30 °, it is preferable to set L = λ.

However, in this case, as shown in FIG. 14, a wavefront B2 traveling in the direction opposite to the wavefront B1 when viewed from the normal direction of the main surface 3a is also generated at the same time. The diffraction angle θ of the wavefront B2 is equal to the diffraction angle θ of the wavefront B1. That is, the wavefront B2 emits in a direction that is line-symmetric with the wavefront B1 with respect to the normal of the main surface 3a. Therefore, the same two-dimensional optical image can be seen by another observer at a position facing the observer A in FIG. Therefore, at each position around the spatial light modulator 3, the two-dimensional light image that should be shown and the two-dimensional light image that should be shown at a position moved by 180 ° from that position appear to overlap.

If such an appearance is acceptable, there is no problem, but in some cases it is not. Therefore, in this embodiment, as shown in FIG. 15, the three areas P ₁ to P ₃ form one unit PU, in each of the plurality of units PU, the phase modulation amount is 0 (rad) the area P _1, the region P ₂ phase modulation amount is 2π / 3 (rad), arranged and a region P ₃ phase modulation amount is 4π / 3 (rad) in this order. _{The region P 1} in which the phase modulation amount is 0 (rad) corresponds to the region E 2a in FIGS. 9 to 12. _{The region P 2} in which the phase modulation amount is 2π / 3 (rad) corresponds to the region E2b of FIGS. 9 to 12. _{The region P 3} having a phase modulation amount of 4π / 3 (rad) corresponds to the region E2c of FIGS. 9 to 12. When the arrangement pitch of the regions P ₁ to P ₃ is L, the period of the pitch or the diffraction grating of each unit PU is 3L (= Λ). Further, the distance between a certain wavefront B1 and the wavefront B1 that occurs next is mλ (m is an integer). That is, the following mathematical formula (2) holds. The pitch L is set to be equal to or longer than the length in the longitudinal direction (first direction D1 in the portion (a) of FIG. 4) of each pixel of the spatial light modulator 3, and in a preferred example, the pitch L is the spatial light modulator. Equal to the longitudinal length of each of the 3 pixels.

FIG. 16 is a graph showing the relationship between the period Λ and the diffraction angle θ (provided that m = 1) when the period Λ of the diffraction grating is normalized by the wavelength λ. Part (a) of FIG. 16 shows a graph having a diffraction angle θ = 0 ° to 90 °, and part (b) of FIG. 16 shows an enlarged portion of the part having a diffraction angle θ = 5 ° to 30 °. Part (c) shows an enlarged portion of the diffraction angle θ = 30 ° to 90 °. With reference to the part (b) of FIG. 16, it can be seen that, for example, in order to realize the diffraction angle θ ≧ 10 °, it is necessary to satisfy Λ ≦ 6λ. In other words, it is desirable that the period Λ of the diffraction grating is 6 times or less the wavelength λ. Thereby, the diffraction angle θ ≧ 10 ° can be realized. Further, referring to the part (c) of FIG. 16, it can be seen that, for example, in order to realize the diffraction angle θ ≧ 30 °, it is necessary to satisfy Λ ≦ 2λ. In other words, it is desirable that the period Λ of the diffraction grating is not more than twice the wavelength λ. Thereby, the diffraction angle θ ≧ 30 ° can be realized.

FIG. 17 is a graph showing the relationship between the pitch L and the diffraction angle θ (provided that m = 1) when the pitch L is normalized by the wavelength λ. Part (a) of FIG. 17 shows a graph with a diffraction angle θ = 0 ° to 70 °, and part (b) of FIG. 17 shows an enlarged portion of the pitch L = 0 to 2λ. Referring to the part (a) of FIG. 17, when the pitch L is larger than 4λ, the diffraction angle θ is less than 5 °. Further, referring to the part (b) of FIG. 17, when L = 0.355λ, θ = 70 °, when L = 0.435λ, θ = 50 °, and when L = 0.667λ, θ = 30 °, L. When = 0.975λ, θ = 20 °, and when L = 1.920λ, θ = 10 °.

FIG. 18 is a graph showing the relationship between the pitch L and the diffraction angle θ (provided that m = 1) when the wavelength λ = 532 nm as an example. Part (a) of FIG. 18 shows a graph with a diffraction angle θ = 0 ° to 70 °, and part (b) of FIG. 18 shows an enlarged portion of the pitch L = 0 nm to 1000 nm. Referring to the part (a) of FIG. 18, when the pitch L is larger than 2 μm, the diffraction angle θ is less than 5 °. Further, referring to the part (b) of FIG. 18, when L = 188.7 nm, θ = 70 °, when L = 231.5 nm, θ = 50 °, when L = 354.7 nm, θ = 30 °, L. When = 518.5 nm, θ = 20 °, and when L = 1021.2 nm, θ = 10 °.

このことを一般化すると、隣接領域のｎ個前（ｎは整数）の波との強め合いによって

を満たす回折角θ_Bを有する波面Ｂ３が生じる。 Here, the presence or absence of another diffraction angle different from the above-mentioned design diffraction angle θ is examined. FIG. 19 is a diagram showing in more detail the relationship between the diffraction angle θ shown in FIG. 15 and _{the phase modulation amount of each region P 1 to} P _3. As shown in the figure, the phase modulation amount of area P ₁ of a certain unit PU 0 °, the phase modulation amount of area P ₂ is (1/3) Λsinθ = Lsinθ = ( 1/3) mλ, region P ₃ phase modulation amount (2/3) Λsinθ = 2Lsinθ = ( 2/3) mλ, when the phase modulation amount of area P ₁ of the adjacent unit PU is Λsinθ = 3Lsinθ = mλ, same pixel adjacent to each other The angle (that is, the diffraction angle) formed by the wave surface B1 and the main surface 3a at the timing (that is, the values of m are equal) is θ. However, the angle formed by the wavefront and the main surface 3a at non-identical timings (that is, the values of m are different) between adjacent pixels can be different diffraction angles. In the example shown in FIG. 20, and wave at certain timing arising from the region P _2, there is shown a wavefront B3 generated by the wave in the previous timing arising from the region P _1, and the wavefront B3 _{The magnitude of the angle θ B} formed by the main surface 3a is different from the above-mentioned diffraction angle θ. It should be noted that this angle θ _B satisfies the following mathematical formula (3).

To generalize this, by strengthening with the wave n before (n is an integer) in the adjacent region.

A wavefront B3 having a _{diffraction angle θ B} that satisfies the condition is generated.

Next, the relationship between the pitch L and the phase difference between adjacent regions for realizing an arbitrary diffraction angle θ will be described. Part (a) of FIG. 21 is a graph showing the relationship between the pitch L satisfying the above equation (2) and the diffraction angle θ when the wavelength λ is 532 nm as an example. Part (b) of FIG. 21 is a graph showing an enlarged portion of the graph of part (a) where the pitch L is up to 2 μm. In these figures, five graphs corresponding to each of m = 1 to 5 are shown. FIG. 22 is a graph plotting the correlation between the phase difference between adjacent regions and the m value. Based on these graphs, for example, in order to realize a diffraction angle θ = 40 ° at m = 1, the pitch L = 276 nm may be set, or in order to realize a diffraction angle θ = 40 ° at m = 2. It can be seen that the pitch L = 552 nm should be set.

In FIG. 23, when the wavelength λ = 532 nm, the pitch L satisfying the equation (2) is obtained when the design diffraction angle θ is given, and the pitch L is further substituted into the following equation (5). It is a figure which shows the result of having obtained the diffraction angle θ _B. The phase difference δφ in the adjacent region was set to 2π / 3. The diffraction angle θ _B when n = 0 coincides with the diffraction angle θ.

As another example, the part (a) in FIG. 24 is a graph showing the relationship between the pitch L satisfying the above equation (2) and the diffraction angle θ when the wavelength λ is 467 nm. Part (b) of FIG. 24 is a graph showing an enlarged portion of the graph of part (a) where the pitch L is up to 2 μm. In these figures, five graphs corresponding to each of m = 1 to 5 are shown. FIG. 25 is a graph plotting the correlation between the phase difference between adjacent regions and the m value. Based on these graphs, for example, in order to realize a diffraction angle θ = 40 ° at m = 1, the pitch L = 242 nm may be set, or in order to realize a diffraction angle θ = 40 ° at m = 2. It can be seen that the pitch L = 484 nm should be set.

In FIG. 26, when the wavelength λ = 467 nm, the pitch L satisfying the equation (2) is obtained when the design diffraction angle θ is given, and the pitch L is further substituted into the above equation (5). It is a figure which shows the result of having obtained the diffraction angle θ _B. The phase difference φ in the adjacent region was set to 2π / 3. The diffraction angle θ _B when n = 0 coincides with the diffraction angle θ.

As yet another example, the part (a) in FIG. 27 is a graph showing the relationship between the pitch L satisfying the above equation (2) and the diffraction angle θ when the wavelength λ is 630 nm. Part (b) of FIG. 27 is a graph showing an enlarged portion of the graph of part (a) where the pitch L is up to 2 μm. In these figures, five graphs corresponding to each of m = 1 to 5 are shown. FIG. 28 is a graph plotting the correlation between the phase difference between adjacent regions and the m value. Based on these graphs, for example, in order to realize a diffraction angle θ = 40 ° at m = 1, the pitch L = 327 nm may be set, or in order to realize a diffraction angle θ = 40 ° at m = 2. It can be seen that the pitch L = 653 nm should be set.

In FIG. 29, when the wavelength λ = 630 nm, the pitch L satisfying the equation (2) is obtained when the design diffraction angle θ is given, and the pitch L is further substituted into the above equation (5). It is a figure which shows the result of having obtained the diffraction angle θ _B. The phase difference φ in the adjacent region was set to 2π / 3. The diffraction angle θ _B when n = 0 coincides with the diffraction angle θ.

Part (a) of FIG. 30 is a diagram showing an example of a suitable diffraction grating based on the above examination results. Part (b) of FIG. 30 is a partially enlarged view of part (a). In these figures, the phase modulation amount is shown by the shade of color, the region where the phase modulation amount is large is shown by a light color, and the region where the phase modulation amount is small is shown by a dark color. As shown in the figure, in this diffraction grating, the region Fa where the phase modulation amount is 0, the region Fb where the phase modulation amount is 2π / 3 (rad), and the phase modulation amount are 4π / 3 (rad). The region Fc, which is, is repeatedly arranged side by side in this order in each lateral direction. In one example, the width (ie, pitch L) of each region Fa to Fc in the arrangement direction of the diffraction grating is 518 nm. In this case, as shown in FIG. 23, the light E1 having a wavelength of λ = 532 nm is deflected at the diffraction angles θ and θ _{B of} 43.2 ° and -20.0 °.

In order to accurately realize a diffraction grating by phase modulation of the spatial light modulator 3, it is preferable to obtain in advance the relationship (γ characteristic) between the phase modulation amount in the spatial light modulator 3 and the light intensity of the address light E2. .. FIG. 31 is a graph conceptually showing the relationship between the phase modulation amount in the spatial light modulator 3 and the light intensity of the address light E2. As shown in the figure, the relationship between the phase modulation amount of the spatial light modulator 3 and the light intensity of the address light E2 is often non-linear.

The diffraction grating pattern included in the address light E2 is realized by adjusting the intensity of the light emitted from the light emitting regions 42b and 42c of the light emitting surface 42a shown in FIG. The light intensity of the light emitting regions 42b and 42c may be adjusted by increasing or decreasing the drive current supplied to each of the light emitting regions 42b and 42c, or the light shielding pattern 80 including the light shielding pattern 80 as shown in the part (a) of FIG. 32 may be used. This may be done by covering the light emitting regions 42b and 42c with a film (or a light shielding plate). The light-shielding pattern shown in part (a) of FIG. 32 includes a plurality of light-shielding regions 81 separated from each other, and the plurality of light-shielding regions 81 are placed on grid points of various grids such as a triangular grid or a square grid. To position. The planar shape of the light-shielding region 81 may be circular as shown in the part (b) of FIG. 32, or may be a quadrangle (for example, a square or a rectangle) as shown in the part (c) of FIG. 32. good. Alternatively, the planar shape of the light-shielding region 81 may be various other shapes. By adjusting the area ratio occupied by the plurality of light-shielding regions 81 (that is, the size and spacing of each light-shielding region 81), the intensity of the light emitted from the light emitting regions 42b and 42c can be adjusted. In order to suppress the diffraction of light, the center spacing (pitch) between the light-shielding regions 81 adjacent to each other is preferably equal to or less than the wavelength of the address light E2. Part (d) of FIG. 32 is a plan view showing an example of a light-shielding film. In this example, the light-shielding pattern 80 is applied to the light-shielding film region Ab corresponding to the region E2b shown in FIGS. 9 to 12. Not limited to this example, in addition to the region Ab, the light-shielding pattern 80 may be applied to at least one of the region Aa of the light-shielding film corresponding to the region E2a and the region Ac of the light-shielding film corresponding to the region E2c. ..

In the above description, the diffraction grating includes a region Fa having a small phase modulation amount (or a phase modulation amount of substantially zero), a region Fb having a slightly large phase modulation amount, and a region Fc having a large phase modulation amount. An example is shown in which a diffraction grating is formed by repeatedly arranging these three regions Fa to Fc in order in the lateral direction. In this case, the diffraction grating pattern of the address light E2 has a configuration in which the light intensity changes periodically in a certain direction, and the light intensity gradually and monotonically increases or decreases in each period, and each period. The number of regions E2a to E2c in which the light intensities are different from each other is 3, and the light intensity changes in two steps. However, the diffraction grating and the address light E2 are not limited to such a form. The diffraction grating is composed of N regions having a longitudinal direction (N is an integer of 3 or more) repeatedly arranged in the lateral direction, and phase modulation is performed from one end to the other end in the arrangement direction of the N regions. The amount may vary monotonically. In other words, the diffraction grating pattern of the address light E2 is composed of N regions having a longitudinal direction repeatedly arranged in the lateral direction in order, and the light intensity gradually increases or decreases in each repetition period. The number of regions in which the light intensities differ from each other in each cycle is N, and the light intensity may change in the (N-1) step in each repetition cycle. Even in this case, it is possible to reduce the deflection of the two-dimensional optical image in the direction opposite to the desired deflection direction (see FIG. 14) and output the stereoscopic image more clearly.

Here, FIGS. 33 and 34 are diagrams conceptually showing a method of determining the amount of phase modulation in each region constituting the diffraction grating. Incidentally, in the diffraction grating of the illustrated example, each unit PU is intended to include four regions P ₁ to P ₄ (i.e. N = 4). In these figures, the horizontal axis represents the position in the periodic direction of the diffraction grating (alignment direction of the region P ₁ to P _4), the vertical axis represents the output phase. When realizing the diffraction grating, it is preferable to monotonically increase the output phase in the diffraction direction as shown in the part (a) of FIG. 33 and the part (a) of FIG. 34. As an example, these figures show the case where the output phase changes linearly in the diffraction direction. Then, in practice, _{the phase modulation amount in each region P 1 to} P ₄ may be the remainder when the output phase is divided by 2π. In the part (a) of FIG. 33 and the part (a) of FIG. 34, the remainder when the output phase is divided by 2π is colored in gray. Also, part (b) of FIG. 33, and part (b) of FIG. 34 is a phase modulation amount of each region P ₁ to P ₄ are shown. In order to make the phase modulation amounts of the unit PUs uniform, the phase difference between the output phases of the unit PUs adjacent to each other is preferably an integral multiple of 2π, and more preferably 2π. This is because if the phase difference between the output phases of the unit PUs adjacent to each other is not an integral multiple of 2π, diffracted light due to the period of the unit PU is generated up to higher-order components and is superimposed on the light E1 as weak noise light. Is.

Further, as described above, the diffraction angle of the light E1 by the spatial light modulator 3 depends on the wavelength of the light E1. Therefore, when the light E1 contains a plurality of wavelength components, the diffraction angle differs for each wavelength component, and the optical images of the wavelength components presented to the observer A are displaced from each other. Therefore, when light E1 contains a plurality of wavelength components, the light E1 is irradiated with each wavelength component in order not at the same time but with an extremely short period, and the lattice spacing is changed according to each wavelength component to make the diffraction angle constant. You should keep it.

Further, in the present embodiment, each pixel 30 of the spatial light modulator 3 has a configuration in which the phase modulation amount is changed according to the intensity of the address light E2, but an independent electrode is arranged for each pixel 30 and is attached to each electrode. The same function can be realized by applying a voltage individually. However, in order to provide an optical image at the height of the eye Aa of the observer A, a relatively large diffraction angle such as 30 ° or more is desired. In that case, the pitch L of each region constituting the diffraction grating is extremely small, about 1 μm to several μm, and the arrangement pitch of the pixels 30 of the spatial light modulator 3 needs to be equal to or less than this pitch L. Is extremely small, and it is difficult to realize it considering the area required for the drive circuit. As in the present embodiment, since the pixel 30 has a configuration in which the phase modulation amount is changed according to the intensity of the address light E2, wiring individually connected to each electrode becomes unnecessary, and the arrangement pitch of the pixel 30 is reduced. Therefore, a relatively large diffraction angle can be realized.

(First modification)
Part (a) and part (b) of FIG. 35 are views showing the configuration of the first modification of the above embodiment. The image output device 1A of the above embodiment may include the micro LED panel 2B shown in the part (a) of FIG. 35 instead of the high-speed projector 2A shown in FIG. The micro LED panel 2B is an example of the image irradiation unit in this modification, and is a self-luminous high-definition display that irradiates the main surface 3a of the spatial light modulator 3 with light E1 including a two-dimensional optical image. be. Also in this modification, the incident direction of the light E1 with respect to the main surface 3a coincides with the normal direction of the main surface 3a of the spatial light modulator 3. The output wavelength and frame rate of the micro LED panel 2B are the same as those of the high-speed projector 2A of the first embodiment.

A filter 15 is provided on the optical path between the micro LED panel 2B and the spatial light modulator 3. The configuration and operation of the filter 15 are the same as those in the first embodiment. In this modification, the lens 16 of the first embodiment (see FIG. 2) may not be arranged. This is because the light from the micro LED panel 2B forms an image on the retina of the eye Aa of the observer A even if it is observed as it is.

Further, the image output device 1A of the above embodiment replaces the high-speed projector 2A shown in FIG. 1 with a plurality of (three in the illustrated example) high-speed projectors 2C to 2E shown in part (b) of FIG. 35 and wavelengths. It may be provided with a synthesis unit 21. The high-speed projectors 2C to 2E are devices that output a two-dimensional optical image having a single wavelength, and their output wavelengths are different from each other. In one example, the high-speed projector 2C outputs a two-dimensional light image in the red region, the high-speed projector 2D outputs a two-dimensional light image in the green region, and the high-speed projector 2E outputs a two-dimensional light image in the blue region. The high-speed projectors 2C to 2E are individually optically coupled to the wavelength synthesizer 21. The wavelength synthesis unit 21 is, for example, a cross dichroic prism, and synthesizes a two-dimensional optical image output from the high-speed projectors 2C to 2E and outputs it as light E1. The cross-dichroic prism has a first multilayer film that reflects light in the blue region and transmits light in the green region, and a second multilayer film that reflects light in the red region and transmits light in the green region. The first and second multilayer films are combined in an X shape.

For example, as in the present modification, the image irradiation unit can have various configurations without being limited to the above embodiment. The image output device 1A can achieve the effect of the above embodiment by providing various image irradiation units for irradiating the main surface 3a of the spatial light modulator 3 with light E1 including a two-dimensional optical image. Further, by synthesizing the light from a plurality of high-speed projectors as in the example shown in the part (b) of FIG. 35, it is possible to effectively increase the speed by several times that of the high-speed projectors.

(Second modification)
Part (a) of FIG. 36 is a side sectional view showing the configuration of the address light irradiation unit 4B as a second modification of the above embodiment, and is a cross-sectional view including the normal of the back surface 3b of the spatial light modulator 3. show. Part (b) of FIG. 36 is a plan view of the light emitting device 41 and the optical member 44 included in the address light irradiation unit 4B, and is a light emitting device 41 and optics seen from the normal direction of the back surface 3b of the spatial light modulator 3. The configuration of the member 44 is shown.

The address light irradiation unit 4B irradiates the back surface 3b of the spatial light modulator 3 with the address light E2 including the diffraction grating pattern. The address light irradiation unit 4B has a light emitting device 41 similar to that of the above embodiment, and instead of the optical system 43 of the above embodiment (see FIG. 2), an optical system including an optical member 44 and an imaging lens 45 is provided. Have. The optical member 44 has a concave mirror 44a arranged in the center of the annular light emitting device 41. The imaging lens 45 is arranged between the optical member 44 and the back surface 3b of the spatial light modulator 3. The concave mirror 44a and the imaging lens 45 optically couple the plurality of light emitting units 42 of the light emitting device 41 with the back surface 3b of the spatial light modulator 3. Specifically, the concave mirror 44a reflects the address light E2 emitted from the light emitting unit 42 toward the back surface 3b of the spatial light modulator 3. The concave mirror 44a and the imaging lens 45 cooperate to form an image of the diffraction grating pattern included in the address light E2 on the back surface 3b. Further, the concave mirror 44a has a curvature that selectively expands only in the vertical direction of the light emitting portion 42. This makes it possible to reduce the length of the light emitting unit 42 in the vertical direction. A cylindrical lens (not shown) may be arranged on the light emitting surface 42a of each light emitting unit 42 in order to selectively enlarge only the light emitting unit 42 in the vertical direction. The cylindrical lens may be realized by using a metal lens composed of sub-wavelength elements.

A rotation drive unit 401 is attached to the optical member 44 via a rotation shaft 402. The rotation shaft 402 extends in the normal direction of the back surface 3b, and is rotated around the axis along the normal direction of the back surface 3b by the driving force from the rotation drive unit 401. As a result, the orientation of the concave mirror 44a is dynamically changed, and the address light E2 from a part of the light emitting portions 42 corresponding to the orientation of the desired diffraction grating pattern selected from the plurality of light emitting portions 42 is spatial. It is input to the back surface 3b of the optical modulator 3. Therefore, it is possible to dynamically change the direction of the diffraction grating pattern on the back surface 3b. In one example, the rotary shaft 402 rotates in one direction by the driving force from the rotary drive unit 401. In that case, the diffraction grating pattern rotates in one direction on the back surface 3b.

Even when the image output device 1A of the above embodiment is provided with the address light irradiation unit 4B of this modification, the same effect as that of the above embodiment can be obtained. In the above embodiment, a part of the light emitting units 42 selected from the plurality of light emitting units 42 corresponding to the direction of the desired diffraction grating pattern outputs the address light E2, but in this modification, the above It may be the same as the embodiment, or all of the plurality of light emitting units 42 may always output the address light E2.

(Third modification example)
Part (a) of FIG. 37 is a side sectional view showing the configuration of the address light irradiation unit 4C as a third modification of the above embodiment, and is along the normal direction of the back surface 3b of the spatial light modulator 3. The cross section is shown. Part (b) of FIG. 37 is a plan view of the light emitting device 46 included in the address light irradiation unit 4C, and shows the configuration of the light emitting device 46 seen from the normal direction of the back surface 3b of the spatial light modulator 3. Part (c) of FIG. 37 is a diagram showing a cross section of the light emitting device 46 along the line I-I of part (b).

The address light irradiation unit 4C irradiates the back surface 3b of the spatial light modulator 3 with the address light E2 including the diffraction grating pattern. The address light irradiation unit 4C of this modification has a light emitting device 46 and an optical system 47. The light emitting device 46 has a disk shape and has a main surface 46a and a back surface 46e opposite to the main surface 46a. Further, the light emitting device 46 has a light emitting unit 46b provided on the main surface 46a. The planar shape of the light emitting portion 46b exhibits an annular shape provided along the circumference. The central axis of this circle coincides with the central axis of the pixel group of the spatial light modulator 3. As shown in the part (c) of FIG. 37, the light emitting part 46b includes a plurality of light emitting regions 46c arranged concentrically. By having such a plurality of concentric light emitting regions 46c, the light emitting unit 46b can output the address light E2 including the diffraction grating pattern whose periodic direction is the radial direction of the circumference. The plurality of light emitting regions 46c may be suitably configured by a surface emitting type semiconductor light emitting device such as a light emitting diode or a surface emitting laser. The surface emitting laser may be a VCSEL, a PCSEL, or an S-iPM laser (described later).

Further, as shown in the part (a) of FIG. 38, the light emitting part 46b may have a single annular light emitting region 46g instead of the plurality of concentric light emitting regions 46c. In that case, the light emitting device 46 may have a periodic structure 46h with a light-shielding film on the main surface 46a. The part (b) in FIG. 38 is a cross-sectional view taken along the line II-II of the part (a) in FIG. 38. The periodic structure 46h is provided on the light emitting surface of the light emitting region 46g, and the opening and the light-shielding portion are periodically repeated according to the diffraction grating pattern. In the illustrated example, the light-shielding portions 461 and 462 corresponding to the regions E2a and E2b shown in FIGS. 9 to 12, respectively, and the opening 463 corresponding to the region E2c are periodically repeated. The light emitting region 46g may be suitably configured by a surface emitting type semiconductor light emitting device such as a light emitting diode or a surface emitting laser. The surface emitting laser may be a VCSEL, a PCSEL, or an S-iPM laser (described later).

Further, the light emitting unit 46b includes a plurality of element electrodes 46d and a conductive film 46f formed on the main surface 46a. In one example, the conductive film 46f is a transparent conductive film and has light transmittance with respect to the wavelength of the address light E2. In addition, in the part (b) of FIG. 37 and the part (a) of FIG. 38, only one element electrode 46d is shown as a representative. The plurality of element electrodes 46d are provided on the back surface 46e of the light emitting device 46, and are arranged side by side in the circumferential direction of the circumference. In one example, the planar shape of each element electrode 46d is a fan shape centered on the center of the annulus of the light emitting portion 46b. These element electrodes 46d provide address light by supplying a drive current between the light emitting portion 46b and the conductive film 46f in the portion of the light emitting portion 46b corresponding to the direction of the desired diffraction grating pattern on the back surface 3b of the spatial light modulator 3. E2 is selectively emitted. This makes it possible to dynamically change the orientation of the diffraction grating pattern on the back surface 3b. In one example, each element electrode 46d makes the light emitting unit 46b emit light in order in the circumferential direction. In that case, the diffraction grating pattern rotates in one direction on the back surface 3b.

The optical system 47 is arranged between the light emitting device 46 and the spatial light modulator 3, and optically couples the light emitting unit 46b and the back surface 3b of the spatial light modulator 3. The optical axis of the optical system 47 coincides with the central axis of the annulus of the light emitting portion 46b, and the shape of the optical system 47 in the cross section including the central axis of the annulus includes, for example, a convex lens. Alternatively, the shape of the optical system 47 in the cross section including the central axis of the annulus may include a metal lens. When the optical system 47 includes a metal lens, the thickness of the optical system 47 in the optical axis direction can be reduced. The shape of the optical system 47 is not limited to these, and various other shapes can be adopted as long as the address light E2 can be imaged on the back surface 3b.

The address light irradiation unit 4A of the above embodiment may be replaced with the address light irradiation unit 4C of this modification. According to the configuration of this modification, the address light irradiation unit 4C that dynamically changes the direction of the diffraction grating pattern on the back surface 3b is on a flat surface without requiring assembly along the circumference, unlike the address light irradiation unit 4A. It can be suitably realized by the process processing of. In the above example, the plurality of element electrodes 46d are provided on the back surface 46e of the light emitting device 46, but the conductive film 46f on the main surface 46a side is divided into the plurality of element electrodes, and a single element electrode 46d is provided on the back surface 46e side. Electrodes may be provided.
(Fourth modification)

FIG. 39 is a diagram schematically showing the configuration of the address light irradiation unit 4D as a fourth modification of the above embodiment. The address light irradiation unit 4D irradiates the back surface 3b of the spatial light modulator 3 with the address light E2 including the diffraction grating pattern. The address light irradiation unit 4D of this modification includes a laser light source 403, a beam expander 404, a polarization beam splitter 405, a half-wave plate (λ / 2 plate) 406, a reflector 407, a tilt mirror 408, and a rotation drive unit 409. Have.

The laser light source 403 outputs the laser light E3 having the same wavelength as the wavelength of the address light E2. The beam expander 404 is optically coupled to the laser light source 403, expands the optical diameter of the laser beam E3 output from the laser light source 403, and outputs the laser beam 403 in parallel.

The polarization beam splitter 405 is an example of a branching portion in this modification, and splits the laser beam E3 output from the laser light source 403 into two laser beams E31 and E32. Specifically, the polarizing beam splitter 405 is optically coupled to the laser light source 403 via the beam expander 404, and the laser light E3 received from the laser light source 403 is transferred to the two laser light E31, depending on the polarization direction. Branch to E32. The polarization direction of the laser beam E3 is tilted at an angle (for example, 45 °) larger than 0 ° and smaller than 90 ° with respect to the polarization direction in which the polarization beam splitter 405 has transmission characteristics. Therefore, the polarization component of the laser beam E3 parallel to the polarization direction in which the polarizing beam splitter 405 has transmission characteristics passes through the polarization beam splitter 405 to become the laser light E31, and is orthogonal to the polarization direction in which the polarization beam splitter 405 has transmission characteristics. The polarization component of the laser light E3 is reflected by the polarizing beam splitter 405 to become the laser light E32.

The half-wave plate 406 is optically coupled to the laser light source 403 via the polarizing beam splitter 405 and the beam expander 404, receives the laser beam E31 output from the polarizing beam splitter 405, and changes the phase by 180 °. The polarization direction of the laser beam E31 is rotated by 90 °. As a result, the polarization direction of the laser beam E31 after passing through the half-wave plate 406 coincides with the polarization direction of the laser beam E32.

The reflecting mirror 407 and the tilting mirror 408 form the interference optical system in this modification. The reflector 407 is optically coupled to the laser light source 403 via the half-wave plate 406 and the polarization beam splitter 405, and the laser light E31 transmitted through the polarization beam splitter 405 and the half-wave plate 406 is transferred to the space light modulator 3. It reflects toward the back surface 3b. The tilt mirror 408 is optically coupled to the laser light source 403 via the polarizing beam splitter 405, and reflects the laser beam E32 branched by the polarizing beam splitter 405 toward the back surface 3b of the spatial light modulator 3. The reflecting mirror 407 and the tilting mirror 408 are arranged so as to face each other, and the laser beams E31 and E32 are directed toward the back surface 3b from opposite directions when viewed from the normal direction of the back surface 3b. The reflecting mirror 407 and the tilting mirror 408 cause the laser beams E31 and E32 branched by the polarization beam splitter 405 to interfere with each other to generate interference fringes on the back surface 3b of the spatial light modulator 3. This interference fringe is used as a diffraction grating pattern of the address light E2 on the back surface 3b.

The rotation drive unit 409 and the tilt mirror 408 form the position change unit in this modification, and dynamically change the relative positional relationship when the laser beams E31 and E32 interfere with each other. Specifically, the tilt mirror 408 is connected to the rotation drive unit 409 via the rotation shaft 410, and receives the driving force of the rotation drive unit 409 to perform a rotation operation around a predetermined axis. Further, the normal direction of the light reflecting surface of the tilting mirror 408 is slightly tilted with respect to a predetermined axis, and when the tilting mirror 408 rotates about the predetermined axis, the optical axis of the laser beam E32 is also minute. Rotate and move with a radius. As a result, the relative position of the irradiation spot of the laser beam E32 to the irradiation spot of the laser beam E31 moves along a certain circle on the back surface 3b of the spatial light modulator 3. Therefore, the diffraction grating pattern of the address light E2, which is the interference fringes of the laser lights E31 and E32, rotates in one direction on the back surface 3b.

As in this modification, the interference fringes may be used as the diffraction grating pattern. In that case, as in this modification, the direction of the interference fringes, that is, diffraction, is obtained by dynamically changing the relative positional relationship at the time of interference between one laser beam E31 and the other laser beam E32 constituting the interference fringes. The orientation of the grating pattern can be changed dynamically. The dynamic change in the orientation of the diffraction grating pattern is not limited to the rotation of the diffraction grating pattern, and may be a rotation operation in a limited angle range. Although the polarizing beam splitter 405 and the half-wave plate 406 are used in the above example, the laser beam E3 may be branched by using a half mirror or the like instead of the polarizing beam splitter. In this case, the half-wave plate 406 becomes unnecessary.
(Fifth modification)

Part (a) of FIG. 40 is a diagram schematically showing the configuration of the address light irradiation unit 4E as a fifth modification of the above embodiment. The address light irradiation unit 4E irradiates the back surface 3b of the spatial light modulator 3 with the address light E2 including the diffraction grating pattern. The address light irradiation unit 4E of this modification has an annular light emitting device 49 and an optical system including an optical member 48 arranged inside the light emitting device 49. Part (b) of FIG. 40 is a plan view of the light emitting device 49 as viewed from the axial direction of the annulus. As shown in the figure, the light emitting device 49 includes a plurality of surface emitting laser element arrays 50. Each surface emitting laser element array 50 is an example of a light emitting unit in this modification. The plurality of surface emitting laser element arrays 50 are arranged side by side along the circumference with the light emitting surface 50a facing inward. The surface emitting laser element array 50 of this modification is formed by arranging a plurality of surface emitting laser elements one-dimensionally or two-dimensionally. Each surface emitting laser element outputs an arbitrary optical image by controlling the phase spectrum and the intensity spectrum of the light emitted from a plurality of emission points arranged in a two-dimensional manner. Such a surface-emitting laser element is called an S-iPM (Static-integrable PhaseModulating) laser, and is a two-dimensional arbitrary-shaped light including a direction perpendicular to the main surface of the semiconductor substrate and a direction inclined with respect to the main surface. The image can be output. Therefore, in the surface emitting laser element array 50, by appropriately designing the phase spectrum and the intensity spectrum of the output light in advance, the diffraction grating pattern (for example, the light intensity as shown in FIGS. 9 to 12) can be obtained in the far-field image. It is possible to form an image of the address light E2 including (a pattern in which three different regions E2a to E2c are repeated in order) on the back surface 3b.

The optical member 48 has a flat reflecting mirror 48a arranged in the center of the annular light emitting device 49. The reflector 48a optically couples the plurality of surface emitting laser element arrays 50 of the light emitting device 49 and the back surface 3b of the spatial light modulator 3. That is, the reflecting mirror 48a reflects the address light E2 emitted from the surface emitting laser element array 50 toward the back surface 3b of the spatial light modulator 3.

A rotation drive unit 401 is attached to the optical member 48 via a rotation shaft 402. The rotation shaft 402 extends in the normal direction of the back surface 3b, and is rotated around the axis along the normal direction of the back surface 3b by the driving force from the rotation drive unit 401. As a result, the orientation of the reflecting mirror 48a dynamically changes, and the surface emitting laser element array 50 selected from the plurality of surface emitting laser element arrays 50 corresponds to the orientation of the desired diffraction grating pattern. The address light E2 can be input to the back surface 3b of the spatial light modulator 3. Therefore, it is possible to dynamically change the direction of the diffraction grating pattern on the back surface 3b. In one example, the rotary shaft 402 rotates in one direction by the driving force from the rotary drive unit 401. In that case, the diffraction grating pattern rotates in one direction on the back surface 3b.

As shown in the part (a) of FIG. 41, the address light E2 may be directly irradiated from the surface emitting laser element array 50 to the back surface 3b without passing through the optical member 48, or (b) of FIG. 41. As shown in the section, the address light E2 may be irradiated from the surface emitting laser element array 50 to the back surface 3b via the lens 54. Further, as shown in the portion (c) of FIG. 41, the metal lens 55 may be formed on the light emitting surface 50a and integrated with the surface emitting laser element array 50. According to the configurations shown in the parts (a) to (c) of FIG. 41, since the optical member 48 is not required, the switching can be performed electrically without the need for a mechanical rotation mechanism. Therefore, the configuration is suitable for increasing the size and speed.

FIG. 42 is a diagram schematically showing the configuration of the address light irradiation unit 4F as another configuration of this modification. The address light irradiation unit 4F also irradiates the back surface 3b of the spatial light modulator 3 with the address light E2 including the diffraction grating pattern. The address light irradiation unit 4F includes a surface emitting laser element array 50 and a rotation drive unit 401. The surface emitting laser element array 50 is arranged below the spatial light modulator 3 so that the light emitting surface 50a faces the back surface 3b of the spatial light modulator 3. A rotation drive unit 401 is attached to the surface emitting laser element array 50 via a rotation shaft 402. The rotation shaft 402 extends in the normal direction of the back surface 3b, and the posture angle around the axis along the normal direction of the back surface 3b is dynamically changed by the driving force from the rotation drive unit 401. As a result, the orientation of the diffraction grating pattern on the back surface 3b changes dynamically. In one example, the rotary shaft 402 rotates in one direction by the driving force from the rotary drive unit 401. In that case, the diffraction grating pattern rotates in one direction on the back surface 3b. In this way, the address light irradiation unit 4F is a light emitting unit (surface emitting laser element array 50) that outputs address light E2 including a diffraction grating pattern, and a drive that dynamically changes the attitude angle of the light emitting unit around the optical axis. It may have a unit (rotation drive unit 401). In this case, an address light irradiation unit that dynamically changes the direction of the diffraction grating pattern on the back surface 3b can be preferably realized. Although the posture angle of the surface emitting laser element array 50 is dynamically changed in this modification, the posture angle of the light emitting unit 42 shown in FIG. 8 is dynamically changed by the same configuration as in this modification. It may be changed.

Here, the surface emitting laser element constituting the surface emitting laser element array 50 will be described in detail. Part (a) of FIG. 43 is a cross-sectional view showing the configuration of the surface emitting laser element 52. An XYZ Cartesian coordinate system is defined in which the axis extending in the thickness direction of the surface emitting laser element 52 passing through the center of the surface emitting laser element 52 is the Z axis. The surface emitting laser element 52 forms a standing wave in the XY in-plane direction, and outputs the address light E2 in a direction (Z direction) perpendicular to the main surface 53a of the semiconductor substrate 53.

The surface emitting laser element 52 has a semiconductor substrate 53 and a semiconductor laminate 60 provided on the main surface 53a of the semiconductor substrate 53. The semiconductor laminate 60 is provided on the clad layer 61 provided on the main surface 53a, the active layer 62 provided on the clad layer 61, the clad layer 63 provided on the active layer 62, and the clad layer 63. It has the contact layer 64 and the contact layer 64. Further, the semiconductor stack 60 has a phase modulation layer 65A. In the illustrated example, the phase modulation layer 65A is provided between the active layer 62 and the clad layer 63, but the phase modulation layer 65A may be provided between the clad layer 61 and the active layer 62. The address light E2 is output from the back surface 53b of the semiconductor substrate 53 and is provided to the spatial light modulator 3. That is, the back surface 53b of the semiconductor substrate 53 corresponds to the light emitting surface 50a in FIGS. 40 and 42.

The energy bandgap of the clad layer 61 and the clad layer 63 is wider than the energy bandgap of the active layer 62. The thickness directions of the semiconductor substrate 53, the clad layers 61 and 63, the active layer 62, the contact layer 64, and the phase modulation layer 65A coincide with the Z-axis direction.

The phase modulation layer 65A is a layer that forms a resonance mode. Part (b) of FIG. 43 is an enlarged cross-sectional view of the phase modulation layer 65A. The phase modulation layer 65A includes a basic layer 65a and a plurality of different refractive index regions 65b. The basic layer 65a is a semiconductor layer made of a first refractive index medium. The plurality of different refractive index regions 65b are composed of a second refractive index medium having a refractive index different from that of the first refractive index medium, and exist in the basic layer 65a. The different refractive index region 65b may be a pore, or may be configured by embedding a compound semiconductor in the pore. The plurality of different refractive index regions 65b are arranged two-dimensionally in a plane (in the XY plane) perpendicular to the thickness direction of the phase modulation layer 65A.

FIG. 44 is a plan view of the phase modulation layer 65A. Here, a virtual square grid in the XY plane is set in the phase modulation layer 65A. It is assumed that one side of the square lattice is parallel to the X-axis and the other side is parallel to the Y-axis. At this time, the square-shaped unit constituent region R centered on the grid point O of the square grid can be set two-dimensionally over a plurality of columns along the X-axis and a plurality of rows along the Y-axis. A plurality of different refractive index regions 65b are provided one by one in each unit constituent region R. The planar shape of the different refractive index region 65b is, for example, a circular shape, but is not limited to this, and may be various shapes such as a polygon, a closed curve, and two or more closed curves. In each unit constituent region R, the center of gravity G of the different refractive index region 65b is arranged away from the grid point O closest to the center of gravity G.

As shown in FIG. 45, the angle formed by the direction from the grid point O toward the center of gravity G and the X axis is φ (x, y). x indicates the position of the x-th grid point on the X-axis, and y indicates the position of the y-th grid point on the Y-axis. When the rotation angle φ is 0 °, the direction of the vector connecting the lattice point O and the center of gravity G coincides with the positive direction of the X axis. Further, let r (x, y) be the length of the vector connecting the grid point O and the center of gravity G. In one example, r (x, y) is constant (over the entire phase modulation layer 65A) regardless of x, y. When the length r (x, y) = 0, the center of gravity G of the different refractive index region 65b coincides with the lattice point O, and the surface emitting laser element 52 becomes a PCSEL.

As shown in FIG. 44, in the phase modulation layer 65A, the rotation angle φ around the grid point O of the center of gravity G of the different refractive index region 65b is independent for each unit constituent region R according to a desired optical image. Is set individually. The rotation angle distribution φ (x, y) has a specific value for each position determined by the values of x and y, but is not always expressed by a specific function. That is, the rotation angle distribution φ (x, y) is determined from the complex amplitude distribution obtained by inverse Fourier transforming the desired optical image from which the phase distribution is extracted. When obtaining the complex amplitude distribution from the desired optical image, the reproducibility of the beam pattern can be improved by applying an iterative algorithm such as the Gerchberg-Saxton (GS) method, which is generally used when calculating hologram generation. improves.

FIG. 46 is a diagram for explaining the relationship between the optical image obtained by forming an image of the output beam pattern of the surface emitting laser element 52 and the rotation angle distribution φ (x, y) in the phase modulation layer 65A. The center Q of the output beam pattern is not always located on the axis perpendicular to the main surface 53a of the semiconductor substrate 53, but may be arranged on the axis perpendicular to the axis. Here, for the sake of explanation, it is assumed that the center Q is on the axis perpendicular to the main surface 53a. FIG. 46 shows four quadrants with the center Q as the origin. FIG. 46 shows a case where an optical image is obtained in the first quadrant and the third quadrant as an example, but it is also possible to obtain an image in the second quadrant and the fourth quadrant or all quadrants. In this modification, as shown in FIG. 46, a point-symmetrical optical image with respect to the origin is obtained. FIG. 46 shows, as an example, a case where the character “A” is obtained in the third quadrant and the character “A” is rotated by 180 degrees in the first quadrant. When the optical images are rotationally symmetric, they are overlapped and observed as one optical image.

The optical image of the output beam pattern of the surface emitting laser element 52 of this modification includes a diffraction grating pattern. Here, in order to obtain a desired optical image including a diffraction grating pattern, the rotation angle distribution φ (x, y) of the different refractive index region 65b of the phase modulation layer 65A is determined by the following procedure.

First, as a first precondition, a Z-axis that coincides with the normal direction and an X-axis and a Y-axis that are orthogonal to each other and coincide with one surface of the phase modulation layer 65A including a plurality of different refractive index regions 65b are included. In the XYZ Cartesian coordinate system defined by the XY plane, M1 (integer of 1 or more) × N1 (integer of 1 or more) unit constituent regions each having a square shape on the XY plane. A virtual square grid composed of R is set.

ａ：仮想的な正方格子の格子定数
λ：面発光レーザ素子５２の発振波長 As a second precondition, the coordinates (ξ, η, ζ) in the XYZ Cartesian coordinate system are, as shown in FIG. 47, the length r of the driving diameter, the inclination angle θ _tilt from the Z axis, and XY. The following equations (6) to (8) are shown for the _{spherical coordinates (r, θ rot} , θ _{tilt ) defined by the rotation angle θ rot} from the X axis specified on the plane and the spherical coordinates (r, θ rot, θ tilt). Suppose the relationship is satisfied. Note that FIG. 47 is a diagram _{for explaining coordinate conversion from spherical coordinates (r, θ rot} , θ _tilt ) to coordinates (ξ, η, ζ) in the XYZ Cartesian coordinate system, and is a diagram for explaining coordinates (ξ, η, ζ). ζ) represents a design optical image on a predetermined plane set in the XYZ Cartesian coordinate system in real space. When a set of bright points towards a beam pattern corresponding to a light image that is output from the surface emitting laser element 52 in the direction defined by the angle theta _tilt and theta _rot, the angle theta _tilt and theta _rot has the following formula ( 9) and the coordinate values k _x on Kx axis corresponding to the X axis a normalized wave number defined by, with corresponding to a normalized wavenumber in the Y axis defined by the following equation (10) Kx and the coordinate values k _y on Ky axis perpendicular to the axis, and shall be converted to. The normalized wave number means a wave number standardized with a wave number of 2π / a corresponding to the grid spacing of a virtual square grid as 1.0. At this time, in the wavenumber space defined by the Kx axis and the Ky axis, the specific wavenumber range including the beam pattern corresponding to the optical image is square M2 (integer of 1 or more) × N2 (integer of 1 or more), respectively. ) Consists of image area FR. The integer M2 does not have to match the integer M1. Similarly, the integer N2 does not have to match the integer N1. Equations (9) and (10) also include, for example, Y. Kurosaka et al., "Effects of non-lasing band intwo-dimensional photonic-crystal lasers clarified using omnidirectional bandstructure," Opt. Express 20, 21773-21783. It is disclosed in (2012).

a: Lattice constant λ of a virtual square lattice: Oscillation wavelength of the surface emitting laser element 52

The as 3 preconditions, in Fourier space, out with coordinate components of Kx axis direction _k x (0 or M2-1 an integer) and Ky-axis direction of the coordinate component _k y (0 or more N2-1 an integer) image area FR _(k x, k _y) identified respectively, X-axis direction of the coordinate component x (0 or M1-1 an integer) and Y-axis direction of the coordinate component y (0 or more N1-1 an integer The complex amplitude F (x, y) obtained by performing a two-dimensional inverse discrete Fourier transform on the unit constituent region R (x, y) on the XY plane specified by) is as follows, with j as an imaginary unit. It is given by the equation (11) of. Further, this complex amplitude F (x, y) is defined by the following equation (12) when the amplitude term is A (x, y) and the phase term is P (x, y). Further, as a fourth precondition, the grid point O (x, y) in which the unit constituent region R (x, y) is parallel to the X-axis and the Y-axis and is the center of the unit constituent region R (x, y), respectively. It is defined by the s-axis and the t-axis that are orthogonal to each other in y).

Under the first to fourth preconditions, the phase modulation layer 65A is configured to satisfy the following first and second conditions. That is, the first condition is that the center of gravity G is arranged in the unit constituent region R (x, y) in a state of being separated from the grid point O (x, y). _{The second condition is that the line segment length r 2} (x, y) from the grid point O (x, y) to the corresponding center of gravity G is set to a value common to each of the unit constituent regions R of M1 × N1. In this state, the angle φ (x, y) formed by the line segment connecting the grid point O (x, y) and the corresponding center of gravity G and the s axis is
φ (x, y) = C × P (x, y) + B
C: Proportional constant, for example 180 ° / π
B: An arbitrary constant, for example 0
The corresponding different refractive index regions 65b are arranged in the unit constituent region R (x, y) so as to satisfy the above relationship.

As a method of obtaining the intensity distribution and the phase distribution from the complex amplitude distribution obtained by the Fourier transform, for example, the intensity distribution I (x, y) is calculated by using the abs function of the numerical analysis software "MATLAB" of MathWorks. The phase distribution P (x, y) can be calculated by using the MATLAB angle function.

Here, when the rotation angle distribution φ (x, y) is obtained from the Fourier transform result of the optical image and the arrangement of each different refraction coefficient region 65b is determined, a general discrete Fourier transform (or fast Fourier transform) is used. Here are some points to keep in mind when calculating. When the optical image before the Fourier transform is divided into four quadrants such as A1, A2, A3, and A4 as in the part (a) of FIG. 48, the obtained beam pattern is as shown in the part (b) of FIG. That is, in the first quadrant of the beam pattern, a pattern in which the first quadrant of the part (a) of FIG. 48 is rotated 180 degrees and the third quadrant of the part (a) of FIG. 48 are superimposed appears, and the beam pattern In the second quadrant, a pattern in which the second quadrant of the part (a) of FIG. 48 is rotated 180 degrees and the fourth quadrant of the part (a) of FIG. 48 are superimposed appears, and the third quadrant of the beam pattern is shown in the figure. A pattern in which the third quadrant of the part (a) of 48 is rotated 180 degrees and the first quadrant of the part (a) of FIG. 48 are superimposed appears, and the part (a) of FIG. 48 appears in the fourth quadrant of the beam pattern. A pattern in which the fourth quadrant of FIG. 48 is rotated 180 degrees and the second quadrant of the part (a) of FIG. 48 is superimposed appears.

Therefore, when an optical image (original optical image) before Fourier conversion that has a value only in the first quadrant is used, the first quadrant of the original optical image appears in the third quadrant of the obtained beam pattern. , A pattern obtained by rotating the first quadrant of the original light image by 180 degrees appears in the first quadrant of the obtained beam pattern.

As described above, in the surface emitting laser element 52, a desired beam pattern can be obtained by phase-modulating the wavefront. This beam pattern is not only a pair of single peak beams (spots), but can also be a diffraction grating pattern as shown in FIGS. 9 to 12, for example.

In this modification, the laser beam output from the active layer 62 enters the inside of the phase modulation layer 65A while being confined between the clad layer 61 and the clad layer 63, depending on the lattice structure inside the phase modulation layer 65A. Form a predetermined mode. The laser light scattered and emitted in the phase modulation layer 65A is output to the outside from the back surface 53b of the semiconductor substrate 53. At this time, the 0th-order light is emitted in the direction perpendicular to the main surface 53a. On the other hand, the +1st order light and the -1st order light are emitted in a two-dimensional arbitrary direction including a direction perpendicular to the main surface 53a and a direction inclined with respect to the main surface 53a.

In the above description in this modification, λ ₀ = a × n (a is a lattice spacing) with _{respect to the wavelength λ 0} , and the band end called _{the Γ 2 point of the square lattice is used.} On the other hand, the grid spacing a _{may be set so that λ 0} = (√2) a × n. This corresponds to the band end called the M point of the square lattice. In this case, for the phase angle distribution φ ₀ (x, y) corresponding to the design beam pattern, the phase of the additional phase angle distribution φ ₁ (x, y) = (± πx / a, ± πy / a) is set. The superimposed phase angle distribution φ (x, y) = φ ₀ (x, y) + φ ₁ (x, y). FIG. 49 is a diagram conceptually showing an example of the rotation angle distribution φ _{1 (x, y).} As shown in FIG. 49, in this example, the first phase value φ _A and the second phase value φ _{B having a} value different from the first phase value φ _A are arranged in a checkered pattern. In one embodiment, the phase value φ _A is 0 (rad) and the phase value φ _B is π (rad). That is, the first phase value φ _A and the second phase value φ _B change by π. In this case, the design beam pattern can be taken out in the vertical direction of the plane, the 0th-order light does not appear in the vertical direction of the plane, and only the design beam pattern consisting of ± 1st-order light can be emitted. The 0th-order light is a wavefront that is not phase-modulated, but the ± 1st-order light is a phase-modulated wavefront. Therefore, the spatial phase distribution of the address light E2 incident on the spatial light modulator 3 can be efficiently controlled.

As in this modification, the light emitting unit that outputs the diffraction grating pattern of the address light E2 may be configured by an S-iPM laser. Even in this case, the same effect as that of the above embodiment can be obtained. Further, in this modification, the resolution can be easily improved by using a plurality of S-iPM lasers side by side at the same time. That is, in order to improve the resolution of the S-iPM laser alone, it is necessary to increase the oscillation region size of the phase modulation layer 65A, but if the oscillation region size is increased, uniform and stable oscillation can be maintained as a whole. It can be difficult. In this modification, the phase of the spatial light modulator 3 is controlled using only the intensity information of the beam pattern output from the S-iPM laser, so that a plurality of S-iPM lasers whose phases do not match each other are simply arranged. Just do it.

To give a specific numerical example, for example, the S-iPM laser described in Y. Kurosaka et al., “Phase-modulating lasers toward on-chip integration”, Scientific Reports 6, 30138 (2016) has a side of 400 μm. A two-dimensional beam pattern with a resolution of 1400 rows and 1400 columns is output from the square oscillation region of. When the optical modulation region of the spatial light modulator 3 is a square with a side of 50 cm, the number of pixels becomes 500,000 in both the row direction and the column direction when the pixels are arranged at a pitch of 1 μm, and the S-iPM laser having the above resolution is used in the row direction. And 357 pieces should be arranged in each row direction. Ideally, it will be a square with a side of 14.3 cm when spread densely. That is, simply by rotating the S-iPM laser array having a side of 14.3 cm, the same function as rotating a holographic plate having a side of 50 cm can be realized, and the size can be increased. In other words, simply by rotating the S-iPM laser array with a side of 30 cm, the same function as rotating a holographic plate with a side of 105 cm can be realized, and the size of the stereoscopic image can be increased by more than 1 m. Will be.

Since the diffraction grating pattern is a repetition of a simple stripe pattern, it is not always necessary to arrange the above number of S-iPM lasers. For example, an optical system including a beam splitter is used to output from a small number of S-iPM lasers. Pattern branching and shifting may be performed. In this case, the number of S-iPM lasers can be reduced by the number of branches.

Further, in the example shown in FIG. 42, instead of the mechanically rotating surface emitting laser element array 50, a plurality of surface emitting laser element arrays 50 corresponding to a plurality of rotation phases may be switched and used. Alternatively, instead of the S-iPM laser, a D-iPM (Dynamic-integrable Phase Modulating) laser capable of dynamically changing the beam pattern may be used. In these cases, the mechanical drive unit can be eliminated, which leads to improvement in reliability. Even when a D-iPM laser is used, since the phase control of the spatial light modulator 3 is performed using only the intensity information of the beam pattern, a plurality of D-iPM lasers whose phases do not match each other are simply arranged side by side. good.

Further, in this modification, the address light E2 from the surface emitting laser element array 50 is directly applied to the back surface 3b of the spatial light modulator 3 without going through the lens optical system. In order to form a finer diffraction grating pattern, a zoom lens optical system composed of a plurality of lenses may be interposed between the surface emitting laser element array 50 and the back surface 3b.

(6th modification)
The S-iPM laser is not limited to the configuration of the fifth modification described above. For example, even with the configuration of the phase modulation layer of this modification, the S-iPM laser can be suitably realized. FIG. 50 is a plan view of the phase modulation layer 65B included in the S-iPM laser. Further, FIG. 51 is a diagram showing the positional relationship of the different refractive index region 65b in the phase modulation layer 65B. The phase modulation layer 65B is a resonance mode forming layer in this modification. As shown in FIGS. 50 and 51, in the phase modulation layer 65B, the center of gravity G of each different refractive index region 65b is arranged on the straight line D. The straight line D is a straight line that passes through the corresponding grid points O of each unit constituent region R and is inclined with respect to each side of the square grid. In other words, the straight line D is a straight line that is inclined with respect to both the X-axis and the Y-axis. The inclination angle of the straight line D with respect to one side (X-axis) of the square lattice is α. The tilt angle α is constant in the phase modulation layer 65B. The tilt angle α satisfies 0 ° <α <90 °, and in one example, α = 45 °. Alternatively, the tilt angle α satisfies 180 ° <α <270 °, and in one example, α = 225 °. When the tilt angle α satisfies 0 ° <α <90 ° or 180 ° <α <270 °, the straight line D extends from the first quadrant to the third quadrant of the coordinate plane defined by the X-axis and the Y-axis. Alternatively, the tilt angle α satisfies 90 ° <α <180 °, and in one example, α = 135 °. Alternatively, the tilt angle α satisfies 270 ° <α <360 °, and in one example, α = 315 °. When the tilt angle α satisfies 90 ° <α <180 ° or 270 ° <α <360 °, the straight line D extends from the second quadrant to the fourth quadrant of the coordinate plane defined by the X-axis and the Y-axis. As described above, the inclination angle α is an angle excluding 0 °, 90 °, 180 ° and 270 °. By setting such an inclination angle α, both the light wave traveling in the X-axis direction and the light wave traveling in the Y-axis direction can be contributed in the light output beam. Here, the distance between the grid point O and the center of gravity G is r (x, y). x indicates the position of the x-th grid point on the X-axis, and y indicates the position of the y-th grid point on the Y-axis. When the distance r (x, y) is a positive value, the center of gravity G is located in the first quadrant (or the second quadrant). When the distance r (x, y) is a negative value, the center of gravity G is located in the third quadrant (or the fourth quadrant). When the distance r (x, y) is 0, the grid point O and the center of gravity G coincide with each other.

の範囲内である。 The distance r (x, y) between the center of gravity G of each different refractive index region 65b and the corresponding lattice point O of each unit constituent region R shown in FIG. 50 is each different refractive index according to a desired optical image. It is set individually for each area 65b. The distribution of the distance r (x, y) has a specific value for each position determined by the values of x and y, but is not always expressed by a specific function. The distribution of the distance r (x, y) is determined from the complex amplitude distribution obtained by inverse Fourier transforming the desired optical image from which the phase distribution is extracted. That is, when the phase P (x, y) at a certain coordinate (x, y) shown in FIG. 51 is P ₀ , the distance r (x, y) is set to 0, and the phase P (x, y) is set. When y) is π + P ₀ , the distance r (x, y) is _{set to the maximum value r 0} , and when the phase P (x, y) is −π + P ₀ , the distance r (x, y) is set. Set to the minimum value -r _0. Then, for the intermediate phase P (x, y), the distance r (x, y) is such that r (x, y) = {P (x, y) −P ₀ } × r _{0 / π.} ). Here, the initial phase P ₀ can be arbitrarily set. Assuming that the grid spacing of the square grid is a, the maximum value r ₀ of r (x, y) is, for example,

Is within the range of.

As in this modification, the surface emitting laser element array 50 may have a phase modulation layer 65B as a resonance mode forming layer. In this case, a part of the laser light (a part of the +1st order light and the -1st order light, and the 0th order light) generated in the phase modulation layer 65B is in a direction not parallel to the main surface 53a of the semiconductor substrate 53. After being diffracted and reflected by the metal electrode film 66 (or directly), it reaches the back surface 53b of the semiconductor substrate 53 and is emitted from the back surface 53b toward the spatial light modulator 3 as address light E2. Also in this modification, the surface emitting laser element array 50 can form an image of the address light E2 including the diffraction grating pattern on the back surface 3b of the spatial light modulator 3. Therefore, the same effect as that of the above embodiment can be obtained.

(7th modification)
In the above embodiment, the liquid crystal type is exemplified as the spatial light modulator 3, but the configuration of the spatial light modulator is not limited to the liquid crystal type. FIG. 52 is a plan view showing the configuration of a reflective dynamic metasurface (hereinafter, simply referred to as a metasurface) 7A as another example of the spatial light modulator. The "meta-surface" is a structure in which a plurality of unit structures sufficiently smaller than the wavelength of light E1 are arranged side by side on a flat surface to change the phase of incident light for each unit structure. There are various structures in the metasurface, and the metasurface of the present embodiment has a structure called a gap plasmon type among them. The metasurface 7A is a flat plate-shaped device extending along the directions D1 and D2 that intersect each other (for example, orthogonally), and the direction D3 that intersects (for example, orthogonally) both directions D1 and D2 is the thickness direction. A plurality of pixels 70 are formed on the main surface 7a of the meta surface 7A. The plurality of pixels 70 are arranged two-dimensionally with the direction D1 as the row direction and the direction D2 as the column direction. The planar shape of each pixel 70 is rectangular (for example, square). The length L of one side of each pixel 70 is, for example, in the range of 200 nm to 400 nm. The metasurface 7A serves as a diffraction grating by individually modulating the phase of the light E1 input to the main surface 7a for each pixel 70.

FIG. 53 is a cross-sectional view taken along the line III-III of FIG. 52 and shows the cross-sectional structure of the metasurface 7A. The metasurface 7A reflects the light E1 including the two-dimensional light image irradiated on the main surface 7a, and modulates the phase of the light E1 for each of a plurality of pixels 70 arranged in a two-dimensional manner. Each pixel 70 of the meta surface 7A has a configuration in which the phase modulation amount is changed according to the intensity of each pixel 70 of the address light E2 emitted from the back surface 7b side. As shown in FIG. 53, the metasurface 7A has a transparent substrate 71, a transparent electrode layer 72, an impedance changing layer 73A, a metal film 74, a laminated structure 75, a metal film 76, and a transparent substrate 77.

The transparent substrate 71 is a plate-shaped member having light transmission. The light transmission here means a property of transmitting the address light E2. In one example, the transparent substrate 71 is a glass substrate. The transparent substrate 71 includes a main surface 71a and a back surface 71b that are parallel to each other and face in opposite directions. The main surface 71a and the back surface 71b are flat and smooth. The back surface 71b coincides with the back surface 7b of the metasurface 7A. The thickness of the transparent substrate 71 is, for example, 20 μm or more and 1 mm or less.

The transparent electrode layer 72 is located between the impedance changing layer 73A and the transparent substrate 71. In the illustrated example, the transparent electrode layer 72 is in contact with the main surface 71a of the transparent substrate 71. The transparent electrode layer 72 has light transmission like the transparent substrate 71. That is, the transparent electrode layer 72 transmits the address light E2. The constituent material of the transparent electrode layer 72 includes, for example, ITO, at least one of zinc oxide-based conductive materials (AZO, GZO). The thickness of the transparent electrode layer 72 is, for example, 1 nm or more and 1 μm or less. The transparent electrode layer 72 is not divided for each pixel, but is integrally provided over the entire surface of the main surface 71a.

The impedance change layer 73A is a semiconductor layer located between the metal film 74 and the transparent electrode layer 72. The impedance change layer 73A expresses an impedance distribution according to the intensity distribution of the address light E2. Specifically, the impedance of the material constituting the impedance changing layer 73A changes monotonically according to the light intensity when receiving light. Examples of such a material include hydrogenated amorphous silicon, GaN-based compounds, InP-based compounds, and GaAs-based compounds. Therefore, the impedance change layer 73A of this modification is at least one of hydrogenated amorphous silicon, a GaN-based compound (for example, i-type GaN), an InP-based compound (for example, i-type InP), and a GaAs-based compound (for example, i-type GaAs). It may be configured to include one. The thickness of the impedance changing layer 73A is, for example, 10 nm or more and 20 μm or less. The impedance change layer 73A is also not divided for each pixel 70, but is integrally provided over the entire surface of the main surface 71a.

The laminated structure 75 is a flat film and extends along the directions D1 and D2 over a plurality of pixels 70. The laminated structure 75 has a main surface 75a and a back surface 75b. Light E1 is input to the main surface 75a. The main surface 75a and the back surface 75b face each other in the direction D3. The distance between the main surface 75a and the back surface 75b (that is, the thickness of the laminated structure 75 in the direction D3) is set sufficiently smaller than the wavelength λ of the light E1. The thickness of the laminated structure 75 is, for example, in the range of 10 nm to 100 nm. The laminated structure 75 has a transparent conductive layer 751 and a dielectric layer 752 laminated with the direction D3 as the laminating direction.

The transparent conductive layer 751 is an inorganic film having light transmittance and conductivity. The term "light transmission" as used herein means a property of transmitting light E1. Further, the conductivity means a property that the electrical resistivity is extremely low (for example, the resistivity is ^10-6 Ω · m or less). The transparent conductive layer 751 of this modification includes, for example, ITO, at least one of zinc oxide-based conductive materials (AZO, GZO). The thickness of the transparent conductive layer 751 is, for example, in the range of 3 nm to 50 nm, and in one example, it is 20 nm.

The dielectric layer 752 is an inorganic film having light transmission and insulating properties. Insulation and the electrical resistivity is extremely high (e.g. resistivity above 10 ⁶ Ω · m) refers to the property. The dielectric layer 752 contains, for example, at least one of _{aluminum oxide (Al 2} O ₃ ), silicon oxide (SiO ₂ ), and magnesium fluoride (Mg F _2). The thickness of the dielectric layer 752 is, for example, in the range of 1 nm to 20 nm, and in one example, it is 5 nm. In the illustrated example, the transparent conductive layer 751 is provided on the back surface 7b side and the dielectric layer 752 is provided on the main surface 7a side, but the transparent conductive layer 751 is provided on the main surface 7a side and is provided on the back surface 7b side. The dielectric layer 752 may be provided.

The metal film 76 has a function as a nano-antenna in the meta-surface structure. The metal film 76 is provided on the main surface 75a of the laminated structure 75. The metal film 76 is a film made of a metal such as gold (Au). The film thickness of the metal film 76 is, for example, in the range of 30 nm to 100 nm, and in one example, it is 50 nm. The metal film 76 is divided into pixels 70. The width of the metal film 76 of each pixel 70 in the direction D1 is set to be smaller than the length (pixel pitch) of the pixels 70 in the same direction, and is set sufficiently smaller than the wavelength λ of the light E1. In one example, the width of the metal film 76 of each pixel 70 is in the range of 40 nm to 360 nm, and in one example it is 250 nm. The distance between the adjacent metal films 76 is in the range of 40 nm to 360 nm, and in one example, it is 150 nm. Further, the ratio (W1 / λ) of the width W1 of the metal film 76 and the wavelength λ of the light E1 is in the range of 0.02 to 1. Further, the ratio (W1 / L) of the width W1 of the metal film 76 to the length L of one side of the pixel 70 is in the range of 0.1 to 0.9.

The metal film 74 is provided on the back surface 75b of the laminated structure 75, and is located between the laminated structure 75 and the impedance changing layer 73A. In one example, the metal film 74 is in contact with the back surface 75b. The metal film 74 reflects the light E1 input to the laminated structure 75 toward the main surface 7a. The metal film 74 is made of a metal such as gold (Au). The film thickness of the metal film 74 is, for example, in the range of 100 nm to 200 nm, and in one example, it is 150 nm. The metal film 74 is divided into pixels 70. In one example, the width of the metal film 74 of each pixel 70 is in the range of 40 nm to 360 nm. Further, the ratio (W2 / L) of the width W2 of the metal film 74 of each pixel 70 to the length L of one side of the pixel 70 is in the range of 0.1 to 0.9.

The transparent substrate 77 is provided on the main surface 75a of the laminated structure 75 so as to cover the metal film 76. In other words, the metal film 76 is provided between the laminated structure 75 and the transparent substrate 77. The transparent substrate 77 is a plate-shaped member having light transmission. The term "light transmission" as used herein means a property of transmitting light E1. In one example, the transparent substrate 77 is a glass substrate. The transparent substrate 77 includes a surface 77a on the opposite side of the laminated structure 75. The surface 77a is flat and smooth and coincides with the main surface 7a of the metasurface 7A. The thickness of the transparent substrate 77 is, for example, 20 μm or more and 1 mm or less.

The operation obtained by the meta-surface 7A having the above configuration will be described. The metasurface 7A has a MIM structure in which a metal film 74 as a light reflecting film, a laminated structure 75 including a transparent conductive layer 751 and a dielectric layer 752, and a metal film 76 as a nanoantenna are laminated in this order. .. In this case, the light E1 incident on the main surface 7a of the metasurface 7A is incident on the portion of the laminated structure 75 exposed on one side of the metal film 76. This light E1 is waveguideed between the metal film 74 and the metal film 76, and is output from the portion of the laminated structure 75 exposed on the other side of the metal film 76 to the outside of the metasurface 7A via the main surface 7a. To. At this time, when a driving voltage is applied between the metal film 76 and the metal film 74, induced currents in opposite directions called a gap surface plasmon mode are generated in both the metal film 76 and the metal film 74. Strong magnetic resonance (plasmon resonance) occurs in the laminated structure 75. By utilizing this magnetic resonance, the phase of the light E1 passing between the metal film 76 and the metal film 74 can be modulated.

数式（１４）から明らかなように、位相変調量φは、積層構造体７５の実効屈折率Ｎ_ｇｓｐに依存する。そして、金属膜７６と金属膜７４との間に印加される駆動電圧を変化させることによって、実効屈折率Ｎ_ｇｓｐを制御することができる。その理由は次の通りである。金属膜７６と金属膜７４との間に駆動電圧が印加されると、金属膜７６と金属膜７４との間の電界によって透明導電層７５１の誘電体層７５２との界面付近の電子密度が高まる。その結果、図５３に示されるように、透明導電層７５１の該界面付近の部分が、実効的に金属化した層７５１ａに変化する。この層７５１ａによって、光Ｅ１に対する積層構造体７５の実効屈折率Ｎ_ｇｓｐが大きく変化する。 Here, the following formula (14) is based on the phase modulation amount φ of the light E1 due to magnetic resonance, the width w (= W1) of the metal film 76, the wavelength λ of the light E1, and the effective refractive index N _{gsp of the laminated structure 75.} Represents the relationship of. In addition, m is an integer.

As is clear from the equation (14), the phase modulation amount φ depends on _{the effective refractive index N gsp of the laminated structure 75. Then, the effective refractive index N gsp} can be controlled by changing the drive voltage applied between the metal film 76 and the metal film 74. The reason is as follows. When a driving voltage is applied between the metal film 76 and the metal film 74, the electric field between the metal film 76 and the metal film 74 increases the electron density near the interface between the transparent conductive layer 751 and the dielectric layer 752. .. As a result, as shown in FIG. 53, the portion of the transparent conductive layer 751 near the interface is transformed into an effectively metallized layer 751a. The layer 751a greatly changes _{the effective refractive index N gsp} of the laminated structure 75 with respect to light E1.

In this modification, an AC voltage source 78 is electrically connected between the metal film 76 and the transparent electrode layer 72, and an AC driving voltage is applied between the metal film 76 and the transparent electrode layer 72. The effective voltage of the AC voltage is, for example, several volts, and the frequency is, for example, DC to 1 GHz. An impedance changing layer 73A is provided between the transparent electrode layer 72 and the metal film 74. When the address light E2 is irradiated on the back surface 3b side, the address light E2 reaches the impedance changing layer 73A and gives an impedance distribution to the impedance changing layer 73A. That is, in the pixel 70 where the light intensity of the address light E2 is low, the impedance of the impedance changing layer 73A is maintained in a large state, and in the pixel 70 where the light intensity of the address light E2 is high, the impedance of the impedance changing layer 73A becomes small (FIG. 53). Region 73a). Therefore, the impedance distribution of the impedance change layer 73A is a distribution corresponding to the intensity distribution of the address light E2. In the pixel 70 in which the impedance of the impedance changing layer 73A is reduced, the voltage applied to the transparent conductive layer 751 is increased, and a strong electric field is applied to the transparent conductive layer 751. Further, in a pixel in which the impedance of the impedance changing layer 73A is maintained in a large state, the impedance of the impedance changing layer 73A is about the same as the impedance of the transparent conductive layer 751, so that the voltage applied to the transparent conductive layer 751 is small and transparent. A weak electric field is applied (or no electric field is applied) to the conductive layer 751. Therefore, a phase distribution corresponding to the light intensity distribution of the address light E2 is given to the light E1. The address light E2 is blocked by the metal film 74 and does not reach the laminated structure 75.

As described above, since each pixel 70 of the metasurface 7A has a configuration in which the phase modulation amount is changed according to the intensity of the address light E2 irradiated on the back surface 7b side of each pixel 70, the metasurface 7A has a diffraction grating. A phase pattern corresponding to the pattern is given to the light E1 incident on the main surface 7a. Therefore, when the two-dimensional light image irradiated to the main surface 7a is reflected by the metasurface 7A, it is output deflected in a direction corresponding to the direction of the diffraction grating pattern. Further, also in this modification, since the direction of the diffraction grating pattern on the back surface 7b changes dynamically as in the above embodiment, the deflection direction of the two-dimensional optical image also changes dynamically. By irradiating the main surface 7a with a two-dimensional light image corresponding to the orientation of the diffraction grating pattern, it becomes possible to present a three-dimensional image to the observer. In addition, according to this image output device, a stereoscopic image is output by dynamically changing the address light E2 including the diffraction grating pattern, so that the stereoscopic image can be produced while the metasurface 7A, which is an optical deflection element, is stationary. It becomes possible to output. Therefore, it is possible to easily increase the size of the metasurface 7A and enlarge the stereoscopic image as compared with the apparatus disclosed in Non-Patent Document 1 in which the holographic screen is mechanically rotated at high speed. Further, by using the metasurface 7A as the spatial light modulator as in this modification, higher speed operation becomes possible as compared with the case where the liquid crystal type spatial light modulator is used.

Also in this modification, the diffraction grating pattern may be rotated on the back surface 7b of the metasurface 7A. In this case, it is possible to present a three-dimensional image in the entire circumferential direction of 360 °. The dynamic change in the orientation of the diffraction grating pattern is not limited to the rotation of the diffraction grating pattern, and may be a rotation operation in a limited angle range.

As in this modification, the metasurface 7A has a metal film 74 located between the main surface 7a and the back surface 7b, a transparent conductive layer 751 located between the metal film 74 and the main surface 7a, and transparent conductivity. An impedance located between the metal film 76 as a nanoantenna located between the layer 751 and the main surface 7a and between the metal film 74 and the back surface 7b and expressing an impedance distribution according to the intensity distribution of the address light E2. It may have a changing layer 73A and a transparent electrode layer 72 located between the impedance changing layer 73A and the back surface 7b. As described above, for example, by having such a configuration in the meta surface 7A, in each pixel 70 of the meta surface 7A, the phase modulation amount is increased according to the intensity of the address light E2 irradiated on the back surface 7b side of each pixel 70. Can be changed.

As in this modification, the impedance change layer 73A may include at least one of hydrogenated amorphous silicon, a GaN-based compound, an InP-based compound, and a GaAs-based compound. The impedance of these substances changes when exposed to light. Therefore, in this case, the impedance change layer 73A that expresses the impedance distribution according to the intensity distribution of the address light E2 can be suitably realized.

FIG. 54 is a cross-sectional view showing the metasurface 7B as another configuration of the metasurface of the seventh modification. The meta-surface 7B differs from the meta-surface 7A in that it has an impedance-changing layer 73B instead of the impedance-changing layer 73A described above. Further, the metasurface 7B further has a transparent conductive layer 79 in addition to the configuration of the metasurface 7A.

The impedance change layer 73B is located between the metal film 74 and the transparent electrode layer 72. The impedance change layer 73B develops an impedance distribution according to the intensity distribution of the address light E2. Specifically, the impedance of the material constituting the impedance changing layer 73B changes monotonically according to the light intensity when receiving light. Examples of such a material include hydrogenated amorphous silicon, GaN-based compounds, InP-based compounds, and GaAs-based compounds. Therefore, the impedance change layer 73B of this modification is at least one of hydrogenated amorphous silicon, a GaN-based compound (for example, i-type GaN), an InP-based compound (for example, i-type InP), and a GaAs-based compound (for example, i-type GaAs). It may be configured to include one. The thickness of the impedance changing layer 73B is, for example, 10 nm or more and 20 μm or less. Further, in order to avoid electrical crosstalk due to carrier diffusion between the impedance changing layers 73B adjacent to each other, a gap GA is provided between the impedance changing layers 73B adjacent to each other.

When the address light E2 is applied to the back surface 3b side, the impedance of the portion is locally lowered. Therefore, the impedance distribution of the impedance change layer 73B is a distribution corresponding to the intensity distribution of the address light E2. In the pixel 70 in which the impedance of the impedance changing layer 73B is reduced, the voltage applied to the transparent conductive layer 751 is increased, and a strong electric field is applied to the transparent conductive layer 751. Further, in the pixel in which the impedance of the impedance changing layer 73B is maintained in a large state, the impedance of the impedance changing layer 73B is larger than the impedance of the transparent conductive layer 751, so that the voltage applied to the transparent conductive layer 751 is small and the transparent conductive layer 751 is transparent. A weak electric field is applied to layer 751 (or no electric field is applied at all). The address light E2 is blocked by the metal film 74 and does not reach the laminated structure 75.

The transparent conductive layer 79 has light transmission and conductivity like the transparent substrate 77. The transparent conductive layer 79 transmits light E1. The constituent material of the transparent conductive layer 79 includes, for example, ITO, at least one of zinc oxide-based conductive materials (AZO, GZO). The thickness of the transparent conductive layer 79 is, for example, 1 nm or more and 1 μm or less. The transparent conductive layer 79 is not divided for each pixel, but is integrally provided over the entire surface of the main surface 71a. The transparent conductive layer 79 is interposed between the metal film 76 and the transparent substrate 77, and is electrically connected to the metal film 76. In one example, the transparent conductive layer 79 is in contact with the metal film 76. The AC voltage source 78 is electrically connected between the transparent electrode layer 72 and the transparent conductive layer 79, and applies an AC voltage between the transparent electrode layer 72 and the transparent conductive layer 79.

Even the meta-surface 7B having the configuration described above can have the same effect as the above-mentioned meta-surface 7A. As shown in the illustrated example, the transparent electrode layer 72, the impedance changing layer 73B, and the laminated structure 75 are divided into pixels 70, and the divided portions may be separated from each other via the gap GA. This makes it possible to suppress electrical crosstalk between adjacent pixels.

The image output device according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, as the spatial light modulator, the liquid crystal type spatial light modulator 3 is exemplified in the above embodiment, and the metasurfaces 7A and 7B are exemplified in the seventh modification, but the spatial light modulator applied to the present invention is. Not limited to these, various other configurations can be applied. Further, the configurations of the address light irradiation unit and the image irradiation unit are not limited to the above-described embodiment and each modification, and various other configurations can be applied.

1A ... image output device, 2A ... high-speed projector, 2B ... micro LED panel, 2C-2E ... high-speed projector, 3 ... spatial light modulator, 4A-4F ... address light irradiation unit, 7A, 7B ... metasurface, 11 ... AC Voltage source, 15 ... filter, 16 ... lens, 21 ... wavelength synthesizer, 30 ... pixel, 31 ... transparent substrate, 32 ... transparent electrode layer, 33 ... impedance change layer, 34 ... dielectric mirror, 35 ... liquid crystal alignment film, 36 ... liquid crystal layer, 36a ... nematic liquid crystal, 37 ... transparent electrode layer, 38 ... transparent substrate, 39 ... ultraviolet curable resin, 39a ... partition wall, 41 ... light emitting device, 42 ... light emitting part, 42a ... light emitting surface, 42b, 42c ... Light emitting region, 43 ... Optical system, 44 ... Optical member, 44a ... Concave mirror, 45 ... Imaging lens, 46 ... Light emitting device, 46a ... Main surface, 46b ... Light emitting part, 46c ... Light emitting region, 46d ... Element electrode, 46e ... Back surface, 46f ... conductive film, 46g ... light emitting region, 46h ... periodic structure, 47 ... optical system, 48 ... optical member, 48a ... reflecting mirror, 49 ... light emitting device, 50 ... surface emitting laser element array, 50a ... light emitting surface, 52 ... Surface emitting laser element, 53 ... Semiconductor substrate, 60 ... Semiconductor laminate, 61 ... Clad layer, 62 ... Active layer, 63 ... Clad layer, 64 ... Contact layer, 65A, 65B ... Phase modulation layer, 65a ... Basic layer, 65b ... Different refractive index region, 66 ... Metal electrode film, 70 ... Pixels, 71 ... Transparent substrate, 72 ... Transparent electrode layer, 73A, 73B ... Impedance change layer, 74 ... Metal film, 75 ... Laminated structure, 76 ... Metal Film, 77 ... transparent substrate, 78 ... AC voltage source, 79 ... transparent conductive layer, 80 ... light-shielding pattern, 81 ... light-shielding region, 301 ... spacer, 401 ... rotation drive unit, 402 ... rotation axis, 403 ... laser light source, 404 ... Beam expander, 405 ... Polarized beam splitter, 406 ... Half-wave plate, 407 ... Reflector, 408 ... Tilt mirror, 409 ... Rotational drive, 410 ... Rotation axis, 751 ... Transparent conductive layer, 752 ... Dielectric layer, A ... Observer, Aa ... Eye, B1-B3 ... Wave surface, D ... Straight line, D1 ... First direction, D2 ... Second direction, Da ... Normal direction, Db ... Light emission direction, E1 ... Optics, E2 ... Address light, E2a~E2c ... area, E3, E31, E32 ... laser light, Fa~Fc ... area, FR ... image area, G ... centroid, GA ... void, O ... grid _{points, P} 1 ~P 4 _... region, PU ... Unit, Q ... Center, R ... Unit constituent area, α ... Tilt angle, θ, θ _B ... Diffraction angle, θ _rot ... Rotation angle, θ _tilt ... Tilt angle.

Claims (18)

A spatial light modulator that has a main surface and a back surface, reflects the light radiated to the main surface, and modulates the phase of the light for each of a plurality of pixels arranged in a two-dimensional manner.
An image irradiation unit that irradiates the main surface with a two-dimensional light image,
An address light irradiation unit that irradiates the back surface with address light including a diffraction grating pattern,
Equipped with
Each pixel of the spatial light modulator has a configuration in which the phase modulation amount is changed according to the intensity of the address light emitted from the back surface side of each pixel.
The address light irradiation unit dynamically changes the direction of the diffraction grating pattern on the back surface.
The image irradiation unit is an image output device that irradiates the main surface with the two-dimensional light image corresponding to the direction of the diffraction grating pattern. The image output device according to claim 1, wherein the address light irradiation unit rotates the diffraction grating pattern on the back surface. The spatial light modulator
A light reflecting layer located between the main surface and the back surface,
A liquid crystal layer located between the light reflecting layer and the main surface,
A light-transmitting first electrode layer located between the liquid crystal layer and the main surface,
An impedance changing layer located between the light reflecting layer and the back surface and exhibiting an impedance distribution according to the intensity distribution of the address light.
A light-transmitting second electrode layer located between the impedance change layer and the back surface,
Have,
The image output device according to claim 1 or 2, wherein the liquid crystal layer has a partition wall for partitioning the liquid crystal for each pixel. The partition wall extends in a first direction along the main surface and in a second direction along the main surface and orthogonal to the first direction.
The image output device according to claim 3, wherein the pitch between the partition walls extending in the second direction is larger than the pitch between the partition walls extending in the first direction. The image output device according to claim 4, wherein the pitch between the partition walls extending in the second direction is at least twice the pitch between the partition walls extending in the first direction. The partition wall extends in a first direction along the main surface and in a second direction along the main surface and orthogonal to the first direction.
The image output device according to claim 3, wherein the pitch between the partition walls extending in the first direction and the pitch between the partition walls extending in the second direction are both 5 μm or less. The image output device according to any one of claims 3 to 6, wherein the impedance changing layer contains at least one of hydrogenated amorphous silicon, a GaN-based compound, an InP-based compound, and a GaAs-based compound. The spatial light modulator
A laminated structure having a transparent conductive layer and a dielectric layer into which the two-dimensional optical image is input to one surface.
A first metal film provided on one surface of the laminated structure and
A second metal film provided on the other surface of the laminated structure facing the one surface and reflecting the two-dimensional optical image input to the laminated structure toward the one surface.
An impedance changing layer provided at a position sandwiching the second metal film between the laminated structure and expressing an impedance distribution according to the intensity distribution of the address light.
A light-transmitting electrode layer provided at a position sandwiching the impedance changing layer between the second metal film and the light-transmitting electrode layer.
Equipped with
In each of the plurality of pixels, the laminated structure includes a pair of portions provided at a pair of positions sandwiching the first metal film when viewed from the stacking direction and exposed from the first metal film.
The image output device according to claim 1 or 2, wherein the first metal film and the second metal film include a plurality of partially metal films provided for each pixel and separated from each other. The address light irradiation unit is
A light emitting unit that outputs the address light including the diffraction grating pattern, and
A drive unit that dynamically changes the attitude angle of the light emitting unit around the optical axis,
The image output device according to any one of claims 1 to 8. The address light irradiation unit is
A plurality of light emitting units arranged side by side along the circumference and capable of outputting the address light including the diffraction grating pattern, respectively.
An optical system that optically couples the plurality of light emitting portions and the back surface thereof,
Have,
In any one of claims 1 to 8, the address light from a part of the light emitting units corresponding to the direction of the diffraction grating pattern selected from the plurality of light emitting units is input to the back surface. The image output device described. The image output device according to claim 10, wherein the optical system includes a metal lens. The address light irradiation unit is
It has a light emitting unit which is provided along the circumference and outputs the address light including the diffraction grating pattern whose periodic direction is the radial direction of the circumference.
15. The image output device according to any one of the following items. The image output device according to any one of claims 9 to 12, wherein the light emitting unit includes a plurality of light emitting regions arranged based on the diffraction grating pattern. The light emitting unit includes a surface emitting laser element having an active layer and a phase modulation layer.
The phase modulation layer includes a basic layer and a plurality of different refractive index regions distributed in a two-dimensional manner in a plane perpendicular to the thickness direction of the phase modulation layer, which has a refractive index different from that of the basic layer.
When a virtual square grid is set in the plane of the phase modulation layer, the centers of gravity of the plurality of different refractive index regions are arranged apart from the grid points of the virtual square grid, and the grid points are arranged. The surrounding rotation angle is set individually for each different refractive index region, or the center of gravity of the plurality of different refractive index regions passes through the grid points of the virtual square grid and is tilted with respect to the square grid. One of claims 9 to 12, which is arranged on a straight line and the distance between the center of gravity of each different refractive index region and the corresponding lattice point is individually set for each different refractive index region. The image output device described in. The light emitting part is
A photonic crystal surface emitting laser device having an active layer and a photonic crystal layer,
A periodic structure provided on the light emitting surface of the photonic crystal surface emitting laser element and periodically repeating an opening and a light-shielding portion according to the diffraction grating pattern.
The image output device according to any one of claims 9 to 12, wherein the image output device has. The address light irradiation unit is
Laser light source and
A branch portion that branches the laser beam output from the laser light source, and a branch portion.
An interference optical system that generates interference fringes by interfering one laser beam branched by the branch portion with the other laser beam.
Have,
The interference optical system includes a position changing portion that dynamically changes the relative positional relationship at the time of interference between the one laser beam and the other laser beam.
The image output device according to any one of claims 1 to 8, wherein the interference fringes are used as the diffraction grating pattern. The diffraction grating pattern has a structure in which the light intensity changes periodically in a certain direction, and the light intensity gradually and monotonically increases or decreases in each period.
The image output device according to any one of claims 1 to 15, wherein the number of regions having different light intensities in each cycle is 3 or more. Further, a filter arranged between the image irradiation unit and the spatial light modulator to reduce the intensity of at least a part of the wavelength components other than visible light contained in the two-dimensional light image is further provided. The image output device according to any one of claims 1 to 17.

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